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  • 1.
    Anguiano, B.
    et al.
    Univ Virginia, Dept Astron, Charlottesville, VA 22904 USA.;Macquarie Univ, Dept Phys & Astron, Balaclava Rd, N Ryde, NSW 2109, Australia..
    Majewski, S. R.
    Univ Virginia, Dept Astron, Charlottesville, VA 22904 USA..
    Allende-Prieto, C.
    Inst Astrofis Canarias, Tenerife 38205, Spain.;Univ La Laguna, Dept Astrofis, E-38206 Tenerife, Spain..
    Meszaros, S.
    Eotvos Lorand Univ, Gothard Astrophys Observ, Szombathely, Hungary.;Hungarian Acad Sci, Budapest, Hungary..
    Jönsson, H.
    Lund Univ, Lund Observ, Dept Astron & Theoret Phys, Box 43, S-22100 Lund, Sweden..
    Garcia-Hernandez, D. A.
    Inst Astrofis Canarias, Tenerife 38205, Spain.;Univ La Laguna, Dept Astrofis, E-38206 Tenerife, Spain..
    Beaton, R. L.
    Princeton Univ, Dept Astrophys Sci, 4 Ivy Lane, Princeton, NJ 08544 USA.;Carnegie Inst Sci, 813 Santa Barbara St, Pasadena, CA 91101 USA..
    Stringfellow, G. S.
    Univ Colorado, Ctr Astrophys & Space Astron, 389 UCB, Boulder, CO 80309 USA..
    Cunha, K.
    Univ Arizona, Tucson, AZ 85719 USA.;Observ Nacl, Rio De Janeiro, Brazil..
    Smith, V. V.
    Natl Opt Astron Observ, Tucson, AZ 85719 USA..
    Comprehensive comparison between APOGEE and LAMOST Radial velocities and atmospheric stellar parameters2018In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 620, article id A76Article in journal (Refereed)
    Abstract [en]

    Context. In the era of massive spectroscopy surveys, automated stellar parameter pipelines and their validation are extremely important for an efficient scientific exploitation of the spectra. Aims. We undertake a critical and comprehensive comparison of the radial velocities and the main stellar atmosphere parameters for stars in common between the latest data releases from the Apache Point Observatory Galaxy Evolution Experiment (APOGEE) and the Large sky Area Multi-Object Spectroscopic Telescope (LAMOST) surveys. Methods. APOGEE is a high-resolution (R = 22500) spectroscopic survey with high signal-to-noise ratio that is part of the Sloan Digital Sky Survey (SDSS). The latest data release, SDSS DR14, comprises APOGEE spectra for 263 444 stars, together with main stellar parameters and individual abundances for up to 20 chemical species. LAMOST is a low-resolution (R = 1800) optical spectroscopic survey also in the Northern Hemisphere, where 4000 fibers can be allocated simultaneously. LAMOST DR3 contains 3 177 995 stars. Results. A total of 42 420 dwarfs and giants stars are in common between the APOGEE DR14 - LAMOST DR3 stellar catalogs. A comparison between APOGEE and LAMOST RVs shows a clear offset of 4.54 +/- 0.03 km s(-1), with a dispersion of 5.8 km s(-1), in the sense that APOGEE radial velocities are higher. We observe a small offset in the effective temperatures of about 13 K, with a scatter of 155 K. A small offset in [Fe/H] of about 0.06 dex together with a scatter of 0.13 dex is also observed. We note that the largest offset between the surveys occurs in the surface gravities. Using only surface gravities in calibrated red giants from APOGEE DR14, with which there are 24 074 stars in common, a deviation of 0.14 dex is found with substantial scatter (0.25 dex). There are 17 482 red giant stars in common between APOGEE DR14 and those in LAMOST tied to APOGEE DR12 via the code called the Cannon. There is generally good agreement between the two data-sets. However, we find that the differences in the stellar parameters depend on effective temperature. For metal-rich stars, a different trend for the [Fe/H] discrepancies is found. Surprisingly, we see no correlation between the internal APOGEE DR14 - DR12 differences in T-eff and those in DR14 - LAMOST tied to DR12, where a correlation should be expected since LAMOST has been calibrated to APOGEE DR12. We find no correlation either between the [Fe/H] discrepancies, suggesting that LAMOST/Cannon is not well coupled to the APOGEE DR12 stellar parameter scale. An [Fe/H] dependence between the stellar parameters in APOGEE DR12 and those in DR14 is reported. We find a weak correlation in the differences between APOGEE DR14 - DR12 and LAMOST on DR12 surface gravity for stars hotter than 4800 K and in the log g range between 2.0 and 2.8 dex. We do not observe an [Fe/H] dependency in the gravity discrepancies.

  • 2. Atalay, B.
    et al.
    Brage, T.
    Jönsson, Per
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Hartman, Henrik
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    MCDHF and RCI calculations of energy levels, lifetimes, and transition rates in Si III and Si IV2019In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, ISSN 0004-6361, Vol. 631, article id A29Article in journal (Refereed)
    Abstract [en]

    We present extensive multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction calculations including 106 states in doubly ionized silicon (Si III) and 45 states in triply ionized silicon (Si IV), which are important for astrophysical determination of plasma properties in different objects. These calculations represents an important extension and improvement of earlier calculations especially for Si III. The calculations are in good agreement with available experiments for excitation energies, transition properties, and lifetimes. Important deviations from the NIST-database for a selection of perturbed Rydberg series are discussed in detail.

  • 3.
    Bijavara Seshashayana, Shilpa
    et al.
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Jönsson, Henrik
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    D'Orazi, V.
    Univ Roma Tor Vergata, Dept Phys, Via Ric Sci 1, I-00133 Rome, Italy.;INAF Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Nandakumar, G.
    Lund Univ, Dept Phys, Div Astrophys, Lund Observ, S-22100 Lund, Sweden..
    Oliva, E.
    INAF Osservatorio Astrofisico Arcetri, Largo Enr Fermi 5, I-50125 Florence, Italy..
    Bragaglia, A.
    INAF Osservatorio Astrofis & Sci Spazio Bologna, Via Piero Gobetti 93-3, I-40129 Bologna, Italy..
    Sanna, N.
    INAF Osservatorio Astrofisico Arcetri, Largo Enr Fermi 5, I-50125 Florence, Italy..
    Romano, D.
    INAF Osservatorio Astrofis & Sci Spazio Bologna, Via Piero Gobetti 93-3, I-40129 Bologna, Italy..
    Spitoni, E.
    INAF Osservatorio Astron Trieste, Via GB Tiepolo 11, I-34131 Trieste, Italy..
    Karakas, A.
    Monash Univ, Sch Phys & Astron, Clayton, Vic 3800, Australia..
    Lugaro, M.
    Monash Univ, Sch Phys & Astron, Clayton, Vic 3800, Australia.;Res Ctr Astron & Earth Sci CSFK, Konkoly Observ, ELKH, Konkoly Thege Mikl Ut 15-17, H-1121 Budapest, Hungary..
    Origlia, L.
    INAF Osservatorio Astrofis & Sci Spazio Bologna, Via Piero Gobetti 93-3, I-40129 Bologna, Italy..
    Stellar Population Astrophysics (SPA) with TNG2024In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 683, article id A218Article in journal (Refereed)
    Abstract [en]

    Context. The age, evolution, and chemical properties of the Galactic disk can be effectively ascertained using open clusters. Within the large program Stellar Populations Astrophysics at the Telescopio Nazionale Galileo, we specifically focused on stars in open clusters, to investigate various astrophysical topics, from the chemical content of very young systems to the abundance patterns of lesser studied intermediate-age and old open clusters.

    Aims. We investigate the astrophysically interesting element fluorine (F), which has an uncertain and intriguing cosmic origin. We also determine the abundance of cerium (Ce), as F abundance is expected to correlate with the s-process elements. We intend to determine the trend of F abundance across the Galactic disk as a function of metallicity and age. This will offer insights into Galactic chemical evolution models, potentially enhancing our comprehension of this element’s cosmic origin.

    Methods. High-resolution near-infrared spectra were obtained using the GIANO-B spectrograph. The Python version of Spectroscopy Made Easy (PySME), was used to derive atmospheric parameters and abundances. The stellar parameters were determined using OH, CN, and CO molecular lines along with Fe I lines. The F and Ce abundances were inferred using two K-band HF lines (λλ 2.28, 2.33 µm) and two atomic H-band lines (λλ 1.66, and 1.71 µm), respectively.

    Results. Of all the clusters in our sample, only King 11 had not been previously studied through medium- to high-resolution spectroscopy, and our stellar parameter and metallicity findings align well with those documented in the literature. We have successfully inferred F and Ce abundances in all seven open clusters and probed the radial and age distributions of abundance ratios. This paper presents the first F Galactic radial abundance gradient. Our results are also compared with literature estimates and with Galactic chemical evolution models that have been generated using different F production channels.

    Conclusions. Our results indicate a constant, solar pattern in the [F/Fe] ratios across clusters of different ages, supporting the latest findings that fluorine levels do not exhibit any secondary behavior for stars with solar or above-solar metallicity. However, an exception to this trend is seen in NGC 6791, a metal-rich, ancient cluster whose chemical composition is distinct due to its enhanced fluorine abundance. This anomaly strengthens the hypothesis that NGC 6791 originated in the inner regions of the Galaxy before migrating to its present position. By comparing our sample stars with the predictions of Galactic chemical evolution models, we came to the conclusion that both asymptotic giant branch stars and massive stars, including a fraction of fast rotators that increase with decreasing metallicity, are needed to explain the cosmic origin of F.

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  • 4.
    Blackwell-Whitehead, R.
    et al.
    Lund Observatory, Box 43, 221 00 Lund, Sweden; Blackett Laboratory, Imperial College London, London SW7 2AZ, UK.
    Pavlenko, Y. V.
    Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield, Hertfordshire AL10 9AB, UK; Main Astronomical Observatory of the Academy of Sciences of Ukraine, Zabolotnoho 27, Kyiv 03680, Ukraine.
    Nave, G.
    Atomic Physics Division, National Institute of Standards and Technology, 100 Bureau Dr., Gaithersburg, MD 20899, USA.
    Pickering, J. C.
    Blackett Laboratory, Imperial College London, London SW7 2AZ, UK.
    Jones, H. R. A.
    Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield, Hertfordshire AL10 9AB, UK.
    Lyubchik, Y.
    Main Astronomical Observatory of the Academy of Sciences of Ukraine, Zabolotnoho 27, Kyiv 03680, Ukraine.
    Nilsson, Hampus
    Lund Observatory, Box 43, 221 00 Lund, Sweden.
    Infrared Mn i laboratory oscillator strengths for the study of late type stars and ultracool dwarfs2010In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 525, p. A44-A44Article in journal (Refereed)
    Abstract [en]

    Aims. The aim of our new laboratory measurements is to measure accurate absolute oscillator strengths for neutral manganese transitions in the infrared needed for the study of late-type stars and ultracool dwarfs.

    Methods. Branching fractions have been measured by high resolution Fourier transform spectroscopy and combined with radiative level lifetimes in the literature to yield oscillator strengths.

    Results. We present experimental oscillator strengths for 20 Mn I transitions in the wavelength range 3216 to 13 997 Å, 15 of which are in the infrared. The transitions at 12 899 Å and 12 975 Å are observed as strong features in the spectra of late-type stars and ultracool dwarfs. We have fitted our calculated spectra to the observed Mn I lines in spectra of late-type stars. Using the new experimentally measured Mn I log (gf) values together with existing data for Mn I hyperfine structure splitting factors we determined the manganese abundance to be log N(Mn) = −6.65 ± 0.05 in the atmosphere of the Sun, log N(Mn) = 6.95 ± 0.20 in the atmosphere of Arcturus, and log N(Mn) = −6.70 ± 0.20 in the atmosphere of M 9.5 dwarf 2MASSW 0140026+270150.

  • 5.
    Burheim, Madeleine
    et al.
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM). Lund Observatory, Division of Astrophysics, Department of Physics, Sölvegatan 27, Box 43, 221 00 Lund, Sweden.
    Hartman, Henrik
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Nilsson, Hampus
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Experimental oscillator strengths of Al I lines for near-infrared astrophysical spectroscopy2023In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 672, article id A197Article in journal (Refereed)
    Abstract [en]

    Context. Elemental abundances can be determined from stellar spectra, making it possible to study galactic formation and evolution. Accurate atomic data is essential for the reliable interpretation and modeling of astrophysical spectra. In this work, we perform laboratory studies on neutral aluminium. This element is found, for example, in young, massive stars and it is a key element for tracing ongoing nucleosynthesis throughout the Galaxy. The near-infrared (NIR) wavelength region is of particular importance, since extinction in this region is lower than for optical wavelengths. This makes the NIR wavelength region a better probe for highly obscured regions, such as those located close to the Galactic center.

    Aims. We investigate the spectrum of neutral aluminium with the aim to provide oscillator strengths (f-values) of improved accuracy for lines in the NIR and optical regions (670–4200 nm).

    Methods. Measurements of high-resolution spectra were performed using a Fourier transform spectrometer and a hollow cathode discharge lamp. The f-values were derived from experimental line intensities combined with published radiative lifetimes.

    Results. We report oscillator strengths for 12 lines in the NIR and optical spectral regions, with an accuracy between 2 and 11%, as well as branching fractions for an additional 16 lines.

     

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  • 6. da Silva, R.
    et al.
    D’Orazi, V.
    Palla, M.
    Bono, G.
    Braga, V. F.
    Fabrizio, M.
    Lemasle, B.
    Spitoni, E.
    Matteucci, F.
    Jönsson, H.
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Kovtyukh, V.
    Magrini, L.
    Bergemann, M.
    Dall’Ora, M.
    Ferraro, I.
    Fiorentino, G.
    François, P.
    Iannicola, G.
    Inno, L.
    Kudritzki, R.-P.
    Matsunaga, N.
    Monelli, M.
    Nonino, M.
    Sneden, C.
    Storm, J.
    Thévénin, F.
    Tsujimoto, T.
    Zocchi, A.
    Oxygen, sulfur, and iron radial abundance gradients of classical Cepheids across the Galactic thin disk2023In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 678, p. A195-A195Article in journal (Refereed)
    Abstract [en]

    Context. Classical Cepheids (CCs) are solid distance indicators and tracers of young stellar populations. Dating back to the beginning of the 20th century, they have been safely adopted to trace the rotation, kinematics, and chemical enrichment history of the Galactic thin disk.

    Aims. The main aim of this investigation is to provide iron, oxygen, and sulfur abundances for the largest and most homogeneous sample of Galactic CCs analyzed so far (1118 spectra of 356 objects). The current sample, containing 70 CCs for which spectroscopic metal abundances are provided for the first time, covers a wide range in galactocentric distances, pulsation modes, and pulsation periods.

    Methods. Optical high-resolution spectra with a high signal-to-noise ratio that were collected with different spectrographs were adopted to provide homogeneous estimates of the atmospheric parameters (effective temperature, surface gravity, and microturbulent velocity) that are required to determine the abundance. Individual distances were based either on trigonometric parallaxes by the Gaia Data Release 3 (Gaia DR3) or on distances based on near-infrared period-luminosity relations.

    Results. We found that iron and α-element radial gradients based on CCs display a well-defined change in the slope for galactocentric distances larger than ~12 kpc. We also found that logarithmic regressions account for the variation in [X/H] abundances from the inner to the outer disk. Radial gradients for the same elements, but based on open clusters covering a wide range in cluster ages, display similar trends. This means that the flattening in the outer disk is an intrinsic feature of the radial gradients because it is independent of age. Empirical evidence indicates that the S radial gradient is steeper than the Fe radial gradient. The difference in the slope is a factor of two in the linear fit (−0.081 vs. −0.041 dex kpc−1) and changes from −1.62 to −0.91 in the logarithmic distance. Moreover, we found that S (explosive nucleosynthesis) is underabundant on average when compared with O (hydrostatic nucleosynthesis). The difference becomes clearer in the metal-poor regime and for the [O/Fe] and [S/Fe] abundance ratios. We performed a detailed comparison with Galactic chemical evolution models and found that a constant star formation efficiency for galactocentric distances larger than 12 kpc accounts for the flattening observed in both iron and α-elements. To further constrain the impact of the predicted S yields for massive stars on radial gradients, we adopted a toy model and found that the flattening in the outermost regions requires a decrease of a factor of four in the current S predictions.

    Conclusions. CCs are solid beacons for tracing the recent chemical enrichment of young stellar populations. Sulfur photospheric abundances, when compared with other α-elements, have the key advantage of being a volatile element. Therefore, stellar S abundances can be directly compared with nebular sulfur abundances in external galaxies.

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  • 7.
    Ekman, Jörgen
    et al.
    Malmö högskola, School of Technology (TS).
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Gustafsson, Stefan
    Malmö högskola, School of Technology (TS).
    Hartman, Henrik
    Malmö högskola, School of Technology (TS).
    Gaigalas, Gediminas
    Godefroid, Michel R.
    Froese Fischer, Charlotte
    Calculations with spectroscopic accuracy: energies, transition rates, and Landé g_J-factors in the carbon isoelectronic sequence from Ar XIII to Zn XXV2014In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 564, article id A24Article in journal (Refereed)
    Abstract [en]

    Extensive self-consistent multiconfiguration Dirac-Hartree-Fock (MCDHF) calculations and subsequent relativistic configuration in- teraction calculations are performed for 262 states belonging to the 15 configurations 2s22p2, 2s2p3, 2p4, 2s22p3l, 2s2p23l, 2p33l and 2s22p4l (l = 0,1,2) in selected carbon-like ions from Ar XIII to Zn XXV. Electron correlation effects are accounted for through large configuration state function expansions. Calculated energy levels are compared with existing theoretical calculations and data from the Chianti and NIST databases. In addition, Landé gJ -factors and radiative electric dipole transition rates are given for all ions. The accuracy of the calculations are high enough to facilitate the identification of observed spectral lines.

  • 8.
    Engström, Lars
    et al.
    Department of Physics, Lund University.
    Lundberg, H
    Department of Physics, Lund University.
    Nilsson, Hampus
    Lund Observatory, Lund University.
    Hartman, Henrik
    Malmö högskola, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM). Lund Observatory, Lund University.
    Bäckström, E
    Department of Physics, Stockholm University.
    The FERRUM project: Experimental transition probabilities from highly excited even 5s levels in Cr ii2014In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 570, article id A34Article in journal (Refereed)
    Abstract [en]

    We report lifetime measurements of the five levels in the 3d4(a5D)5s e6D term in Cr ii at an energy around 83 000 cm-1, and log(g f ) values for 38 transitions from the investigated levels. The lifetimes are obtained using time-resolved, laser-induced fluorescence on ions from a laser-produced plasma. Since the levels have the same parity as the low-lying states directly populated in the plasma, we used a two-photon excitation scheme. This process is greatly facilitated by the presence of the 3d4(a5D)4p z6F levels at roughly half the energy di erence. The f -values are obtained by combining the experimental lifetimes with branching fractions derived using relative intensities from a hollow cathode lamp recorded with a Fourier transform spectrometer.

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  • 9.
    Eriksson, M.
    et al.
    University of Kalmar, 391 82 Kalmar, Sweden; Space Telescope Science Institute, 3700 San Martin drive, Baltimore, MD 21218, USA.
    Nilsson, Hampus
    Atomic Astrophysics, Lund Observatory, Box 43, 221 00 Lund, Sweden.
    Veenhuizen, H.
    University of Kalmar, 391 82 Kalmar.
    Long, K. S.
    Space Telescope Science Institute, 3700 San Martin drive, Baltimore, MD 21218, USA.
    Modeling of C IV pumped fluorescence of Fe II in symbiotic stars2007In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 477, no 1, p. 255-265Article in journal (Refereed)
  • 10.
    Forsberg, R.
    et al.
    Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, 221 00 Lund, Sweden.
    Jönsson, Henrik
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM). Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, 221 00 Lund, Sweden.
    Ryde, N.
    Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, 221 00 Lund, Sweden; Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Bd de l’Observatoire, CS 34229, 06304 Nice Cedex 4, France.
    Matteucci, F.
    Dipartimento di Fisica, Sezione di Astronomia, Università di Trieste, via G.B. Tiepolo 11, 34131 Trieste, Italy; INAF – Osservatorio Astronomico di Trieste, via G.B. Tiepolo 11, 34131 Trieste, Italy; INFN – Sezione di Trieste, via Valerio 2, 34134 Trieste, Italy.
    Abundances of disk and bulge giants from high-resolution optical spectra IV. Zr, La, Ce, Eu2019In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 631, article id A113Article in journal (Refereed)
    Abstract [en]

    Context. Observations of the Galactic bulge suggest that the disk formed through secular evolution rather than gas dissipation and/or mergers, as previously believed. This would imply very similar chemistry in the disk and bulge. Some elements, such as the alpha-elements, are well studied in the bulge, but others like the neutron-capture elements are much less well explored. Stellar mass and metallicity are factors that affect the neutron-capture process. Due to this, the enrichment of the ISM and the abundance of neutron-capture elements vary with time, making them suitable probes for Galactic chemical evolution. Aims. In this work, we make a differential comparison of neutron-capture element abundances determined in the local disk(s) and the bulge, focusing on minimising possible systematic effects in the analysis, with the aim of finding possible differences/similarities between the populations. Methods. Abundances are determined for Zr, La, Ce, and Eu in 45 bulge giants and 291 local disk giants, from high-resolution optical spectra. The abundances are determined by fitting synthetic spectra using the SME-code. The disk sample is separated into thin- and thick-disk components using a combination of abundances and kinematics. Results. We find flat Zr, La, and Ce trends in the bulge, with a similar to 0.1 dex higher La abundance compared with the disk, possibly indicating a higher s-process contribution for La in the bulge. [Eu/Fe] decreases with increasing [Fe/H], with a plateau at around [Fe/H] similar to -0.4, pointing at similar enrichment to alpha-elements in all populations. Conclusions. We find that the r-process dominated the neutron-capture production at early times both in the disks and bulge. Further, [La/Eu] ratios for the bulge are systematically higher than for the thick disk, pointing to either a) a different amount of SN II or b) a different contribution of the s-process in the two populations. Considering [(La+Ce)/Zr], the bulge and the thick disk follow each other closely, suggesting a similar ratio of high-to-low-mass asymptotic giant branch stars.

  • 11.
    Forsberg, R.
    et al.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden..
    Rich, R. M.
    ICLA, Dept Phys & Astron, 430 Portola Plaza,Box 951547, Los Angeles, CA 90095 USA.;Univ Cote Azur, Observ Cote Azur, Lab Lagrange, CNRS, Blvd Observ, F-06304 Nice, France..
    Nieuwmunster, N.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden.;Univ Cote Azur, Observ Cote Azur, Lab Lagrange, CNRS, Blvd Observ, F-06304 Nice, France..
    Jönsson, Henrik
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Schultheis, M.
    Univ Cote Azur, Observ Cote Azur, Lab Lagrange, CNRS, Blvd Observ, F-06304 Nice, France..
    Ryde, N.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden..
    Thorsbro, B.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden.;Univ Tokyo, Sch Sci, Dept Astron, 7-3-1 Hongo,Bunkyo ku, Tokyo 1130033, Japan..
    First r-process enhanced star confirmed as a member of the Galactic bulge2023In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 669, article id A17Article in journal (Refereed)
    Abstract [en]

    Aims. Stars with strong enhancements of r-process elements are rare and tend to be metal-poor, generally with [Fe/H] < -2 dex, and located in the halo. In this work, we aim to investigate a candidate r-process enriched bulge star with a relatively high metallicity of [Fe/H] similar to - 0.65 dex and to compare it with a previously published r-rich candidate star in the bulge. Methods. We reconsidered the abundance analysis of a high-resolution optical spectrum of the red-giant star 2MASS J18082459-2548444 and determined its europium (Eu) and molybdenum (Mo) abundance, using stellar parameters from five different previous studies. Applying 2MASS photometry, Gaia astrometry, and kinematics, we estimated the distance, orbits, and population membership of 2MASS J18082459-2548444 and a previously reported r-enriched star 2MASS J18174532-3353235. Results. We find that 2MASS J18082459-2548444 is a relatively metal-rich, enriched r-process star that is enhanced in Eu and Mo, but not substantially enhanced in s-process elements. There is a high probability that it has a Galactic bulge membership, based on its distance and orbit. We find that both stars show r-process enhancement with elevated [Eu/Fe]-values, even though 2MASS J18174532-3353235 is 1 dex lower in metallicity. Additionally, we find that the plausible origins of 2MASS J18174532-3353235 to be either that of the halo or the thick disc. Conclusions. We conclude that 2MASS J18082459-2548444 represents the first example of a confirmed r-process enhanced star confined to the inner bulge. We assume it is possibly a relic from a period of enrichment associated with the formation of the bar.

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  • 12.
    Forsberg, R.
    et al.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden..
    Ryde, N.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden..
    Jönsson, Henrik
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Rich, R. M.
    ICLA, Dept Phys & Astron, 430 Portola Plaza,Box 951547, Los Angeles, CA 90095 USA..
    Johansen, A.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden.;Globe Inst Univ Copenhagen, Ctr Star & Planet Format, Oster Voldgade 5-7, DK-1350 Copenhagen, Denmark..
    Abundances of disk and bulge giants from high-resolution optical spectra V. Molybdenum: The p-process element2022In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 666, article id A125Article in journal (Refereed)
    Abstract [en]

    Aims. In this work, we aim to make a differential comparison of the neutron-capture and p-process element molybdenum (Mo) in the stellar populations in the local disk(s) and the bulge, focusing on minimising possible systematic effects in the analysis. Methods. The stellar sample consists of 45 bulge and 291 local disk K-giants observed with high-resolution optical spectra. The abundances are determined by fitting synthetic spectra using the Spectroscopy Made Easy (SME) code. The disk sample is separated into thin and thick disk components using a combination of abundances and kinematics. The cosmic origin of Mo is investigated and discussed by comparing with published abundances of Mo and the neutron-capture elements cerium (Ce) and europium (Eu). Results. We determine reliable Mo abundances for 35 bulge and 282 disk giants with a typical uncertainty of [Mo/Fe] similar to 0.2 and similar to 0.1 dex for the bulge and disk, respectively. Conclusions. We find that the bulge is possibly enhanced in [Mo/Fe] compared to the thick disk, which we do not observe in either [Ce/Fe] or [Eu/Fe]. This might suggest a higher past star-formation rate in the bulge; however, as we do not observe the bulge to be enhanced in [Eu/Fe], the origin of the molybdenum enhancement is yet to be constrained. Although the scatter is large, we may be observing evidence of the p-process contributing to the heavy element production in the chemical evolution of the bulge.

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  • 13.
    Geisler, D.
    et al.
    Univ Concepcion, Dept Astron, Casilla 160-C, Concepcion, Chile.;Univ La Serena, Inst Invest Multidisciplinario Ciencia & Tecnol, Ave Raul Bitran S-N, La Serena, Chile.;Univ La Serena, Fac Ciencias, Dept Astron, Av Juan Cisternas 1200, La Serena, Chile..
    Villanova, S.
    Univ Concepcion, Dept Astron, Casilla 160-C, Concepcion, Chile..
    O'Connell, J. E.
    Univ Concepcion, Dept Astron, Casilla 160-C, Concepcion, Chile..
    Cohen, R. E.
    Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA..
    Moni Bidin, C.
    Univ Catolica Norte, Inst Astron, Av Angamos 0610, Antofagasta, Chile..
    Fernandez-Trincado, J. G.
    Univ Catolica Norte, Inst Astron, Av Angamos 0610, Antofagasta, Chile.;Univ Atacama, Inst Astron & Ciencias Planetarias, Copayapu 485, Copiapo, Chile..
    Munoz, C.
    Univ Concepcion, Dept Astron, Casilla 160-C, Concepcion, Chile.;Univ La Serena, Inst Invest Multidisciplinario Ciencia & Tecnol, Ave Raul Bitran S-N, La Serena, Chile.;Univ La Serena, Fac Ciencias, Dept Astron, Av Juan Cisternas 1200, La Serena, Chile..
    Minniti, D.
    Millennium Inst Astrophys, Santiago, Chile.;Univ Andres Bello, Fac Ciencias Exactas, Dept Ciencias Fis, Fernandez Concha 700, Santiago, Chile.;Vatican Observ, I-00120 Vatican City, Vatican..
    Zoccali, M.
    Millennium Inst Astrophys, Santiago, Chile.;Pontificia Univ Catolica Chile, Inst Astrofis, Av Vicuna Mackenna 4860, Santiago 7820436, Chile..
    Rojas-Arriagada, A.
    Millennium Inst Astrophys, Santiago, Chile.;Pontificia Univ Catolica Chile, Inst Astrofis, Av Vicuna Mackenna 4860, Santiago 7820436, Chile..
    Ramos, R. Contreras
    Millennium Inst Astrophys, Santiago, Chile.;Pontificia Univ Catolica Chile, Inst Astrofis, Av Vicuna Mackenna 4860, Santiago 7820436, Chile..
    Catelan, M.
    Millennium Inst Astrophys, Santiago, Chile.;Pontificia Univ Catolica Chile, Inst Astrofis, Av Vicuna Mackenna 4860, Santiago 7820436, Chile.;Pontificia Univ Catolica Chile, Ctr Astroingn, Av Vicuna Mackenna 4860, Santiago 7820436, Chile..
    Mauro, F.
    Univ Catolica Norte, Inst Astron, Av Angamos 0610, Antofagasta, Chile..
    Cortes, C.
    Millennium Inst Astrophys, Santiago, Chile.;Univ Metropolitana Educ, Dept Fis, Fac Ciencias Basicas, Av Jose Pedro Alessandri 774, Santiago 7760197, Chile..
    Ferreira Lopes, C. E.
    Natl Inst Space Res INPE MCTI, Av Astronautas 1758, BR-12227010 Sao Jose Dos Campos, SP, Brazil..
    Arentsen, A.
    Univ Strasbourg, Observ Astron Strasbourg, CNRS, UMR 7550, F-67000 Strasbourg, France..
    Starkenburg, E.
    Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany.;Univ Groningen, Kapteyn Astron Inst, Landleven 12, NL-9747 AD Groningen, Netherlands..
    Martin, N. F.
    Univ Strasbourg, Observ Astron Strasbourg, CNRS, UMR 7550, F-67000 Strasbourg, France.;Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany..
    Tang, B.
    Sun Yat Sen Univ, Sch Phys & Astron, Zhuhai 519082, Peoples R China..
    Parisi, C.
    Univ Nacl Cordoba, Observ Astron, Laprida 854,X5000BGR, Cordoba, Argentina.;UNC, Inst Astron Teor & Expt, CONICET, Laprida 854,X5000BGR, Cordoba, Argentina..
    Alonso-Garcia, J.
    Millennium Inst Astrophys, Santiago, Chile.;Univ Antofagasta, Ctr Astron CITEVA, Av Angamos 601, Antofagasta, Chile..
    Gran, F.
    Millennium Inst Astrophys, Santiago, Chile.;Pontificia Univ Catolica Chile, Inst Astrofis, Av Vicuna Mackenna 4860, Santiago 7820436, Chile.;ESO Vitacura, Alonso de Cordova 3107, Santiago, Chile..
    Cunha, K.
    Univ Arizona, Steward Observ, 933 North Cherry Ave, Tucson, AZ 85721 USA.;Observ Nacl, Rua Gen Jose Cristino 77, BR-20921400 Rio De Janeiro, RJ, Brazil..
    Smith, V
    Natl Opt Astron Observ, 950 North Cherry Ave, Tucson, AZ 85719 USA..
    Majewski, S. R.
    Univ Virginia, Dept Astron, Charlottesville, VA 22904 USA..
    Jönsson, Henrik
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Garcia-Hernandez, D. A.
    Inst Astrofis Canarias IAC, Tenerife 38205, Spain.;Univ La Laguna ULL, Dept Astrofis, Tenerife 38206, Spain..
    Horta, D.
    Liverpool John Moores Univ, Astrophys Res Inst, 146 Brownlow Hill, Liverpool L3 5RF, Merseyside, England..
    Meszaros, S.
    Eotvos Lorand Univ, Gothard Astrophys Observ, Szent Imre H St 112, H-9700 Szombathely, Hungary.;MTA ELTE Exoplanet Res Grp, Szombathely, Hungary..
    Monaco, L.
    Univ Andres Bello, Fac Ciencias Exactas, Dept Ciencias Fis, Fernandez Concha 700, Santiago, Chile..
    Monachesi, A.
    Univ La Serena, Inst Invest Multidisciplinario Ciencia & Tecnol, Ave Raul Bitran S-N, La Serena, Chile.;Univ La Serena, Fac Ciencias, Dept Astron, Av Juan Cisternas 1200, La Serena, Chile..
    Munoz, R. R.
    Univ Chile, Dept Astron, Camino Observ 1515, Santiago, Chile..
    Brownstein, J.
    Univ Utah, Dept Phys & Astron, 115 S 1400 E, Salt Lake City, UT 84112 USA..
    Beers, T. C.
    Univ Notre Dame, Dept Phys, Notre Dame, IN 46556 USA.;Univ Notre Dame, JINA Ctr Evolut Elements, Notre Dame, IN 46556 USA..
    Lane, R. R.
    Univ Bernardo O Higgins, Ctr Invest Astron, Ave Viel 1497, Santiago, Chile..
    Barbuy, B.
    Univ Sao Paulo, IAG, Rua Matao 1226,Cidade Univ, BR-05508900 Sao Paulo, Brazil..
    Sobeck, J.
    Univ Washington, Dept Astron, Seattle, WA 98195 USA..
    Henao, L.
    Univ Concepcion, Dept Astron, Casilla 160-C, Concepcion, Chile..
    Gonzalez-Diaz, D.
    Univ Catolica Norte, Inst Astron, Av Angamos 0610, Antofagasta, Chile.;Univ Antioquia, Inst Fis, Calle 70,52-21, Medellin, Colombia..
    Miranda, R. E.
    Univ Catolica Norte, Inst Astron, Av Angamos 0610, Antofagasta, Chile..
    Reinarz, Y.
    Univ Catolica Norte, Inst Astron, Av Angamos 0610, Antofagasta, Chile..
    Santander, T. A.
    Univ Catolica Norte, Inst Astron, Av Angamos 0610, Antofagasta, Chile..
    CAPOS: The bulge Cluster APOgee Survey I. Overview and initial ASPCAP results2021In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 652, article id A157Article in journal (Refereed)
    Abstract [en]

    Context. Bulge globular clusters (BGCs) are exceptional tracers of the formation and chemodynamical evolution of this oldest Galactic component. However, until now, observational difficulties have prevented us from taking full advantage of these powerful Galactic archeological tools. Aims. CAPOS, the bulge Cluster APOgee Survey, addresses this key topic by observing a large number of BGCs, most of which have only been poorly studied previously. Even their most basic parameters, such as metallicity, [alpha/Fe], and radial velocity, are generally very uncertain. We aim to obtain accurate mean values for these parameters, as well as abundances for a number of other elements, and explore multiple populations. In this first paper, we describe the CAPOS project and present initial results for seven BGCs. Methods. CAPOS uses the APOGEE-2S spectrograph observing in the H band to penetrate obscuring dust toward the bulge. For this initial paper, we use abundances derived from ASPCAP, the APOGEE pipeline. Results. We derive mean [Fe/H] values of -0.85 +/- 0.04 (Terzan 2), -1.40 +/- 0.05 (Terzan 4), -1.20 +/- 0.10 (HP 1), -1.40 +/- 0.07 (Terzan 9), -1.07 +/- 0.09 (Djorg 2), -1.06 +/- 0.06 (NGC 6540), and -1.11 +/- 0.04 (NGC 6642) from three to ten stars per cluster. We determine mean abundances for eleven other elements plus the mean [alpha/Fe] and radial velocity. CAPOS clusters significantly increase the sample of well-studied Main Bulge globular clusters (GCs) and also extend them to lower metallicity. We reinforce the finding that Main Bulge and Main Disk GCs, formed in situ, have [Si/Fe] abundances slightly higher than their accreted counterparts at the same metallicity. We investigate multiple populations and find our clusters generally follow the light-element (anti)correlation trends of previous studies of GCs of similar metallicity. We finally explore the abundances of the iron-peak elements Mn and Ni and compare their trends with field populations. Conclusions. CAPOS is proving to be an unprecedented resource for greatly improving our knowledge of the formation and evolution of BGCs and the bulge itself.

  • 14.
    Gilmore, G.
    et al.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Randich, S.
    INAF Osservatorio Astrofis Arcetri, Largo E Fermi 5, I-50125 Florence, Italy..
    Worley, C. C.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Hourihane, A.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Gonneau, A.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Sacco, G. G.
    INAF Osservatorio Astrofis Arcetri, Largo E Fermi 5, I-50125 Florence, Italy..
    Lewis, J. R.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Magrini, L.
    INAF Osservatorio Astrofis Arcetri, Largo E Fermi 5, I-50125 Florence, Italy..
    Francois, P.
    Univ Paris Diderot, PSL Res Univ, Observ Paris, Sorbonne Paris Cite,GEPI,CNRS, 61 Ave Observ, F-75014 Paris, France..
    Jeffries, R. D.
    Keele Univ, Astrophys Grp, Keele ST55BG, Staffs, England..
    Koposov, S. E.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.;Univ Edinburgh, Inst Astron, Royal Observ, Blackford Hill, Edinburgh EH9 3HJ, Midlothian, Scotland..
    Bragaglia, A.
    INAF Osservatorio Astrofis & Sci Spazio, Via P Gobetti 93-3, I-40129 Bologna, Italy..
    Alfaro, E. J.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron S-N, Granada 18008, Spain..
    Allende Prieto, C.
    Inst Astrofis Canarias, Via Lactea S-N, Tenerife 38205, Spain.;Univ La Laguna, Dept Astrofis, Tenerife 38205, Spain..
    Blomme, R.
    Rob Royal Observ Belgium, Ringlaan 3, B-1180 Brussels, Belgium..
    Korn, A. J.
    Uppsala Univ, Dept Phys & Astron, Div Astron & Space Phys, Observat Astrophys, Box 516, S-75120 Uppsala, Sweden..
    Lanzafame, A. C.
    Univ Catania, Sez Astrofis, Dipartimento Fis & Astron, Via S Sofia 78, I-95123 Catania, Italy..
    Pancino, E.
    INAF Osservatorio Astrofis Arcetri, Largo E Fermi 5, I-50125 Florence, Italy.;Agenzia Spaziale Italiana, Space Sci Data Ctr, Via Politecn Snc, I-00133 Rome, Italy..
    Recio-Blanco, A.
    Univ Cote dAzur, Lab Oratoire Lagrange, CNRS, Observ Cote dAzur, Bd Observ,CS 34229, F-34229 Nice, France..
    Smiljanic, R.
    Polish Acad Sci, Nicolaus Copernicus Astron Ctr, Ul Bartycka 18, PL-00716 Warsaw, Poland..
    Van Eck, S.
    Univ Libre Bruxelles, Inst Astron & Astrophys, CP 226,Blvd Triomphe, B-1050 Brussels, Belgium..
    Zwitter, T.
    Univ Ljubljana, Fac Math & Phys, Jadranska 19, Ljubljana 1000, Slovenia..
    Bensby, T.
    Lund Observ, Dept Astron & Theoret Phys, Box 43, S-22100 Lund, Sweden..
    Flaccomio, E.
    INAF Osservatorio Asron Palermo, Piazza Parlamento, I-190134 Palermo, Italy..
    Irwin, M. J.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Franciosini, E.
    INAF Osservatorio Astrofis Arcetri, Largo E Fermi 5, I-50125 Florence, Italy..
    Morbidelli, L.
    INAF Osservatorio Astrofis Arcetri, Largo E Fermi 5, I-50125 Florence, Italy..
    Damiani, F.
    INAF Osservatorio Asron Palermo, Piazza Parlamento, I-190134 Palermo, Italy..
    Bonito, R.
    INAF Osservatorio Asron Palermo, Piazza Parlamento, I-190134 Palermo, Italy..
    Friel, E. D.
    Indiana Univ, Astron Dept, 727 East 3rd St, Bloomington, IN 47405 USA..
    Vink, J. S.
    Armagh Observ & Planetarium, Coll Hill, Armagh BT61 9DG, North Ireland..
    Prisinzano, L.
    INAF Osservatorio Asron Palermo, Piazza Parlamento, I-190134 Palermo, Italy..
    Abbas, U.
    INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy..
    Hatzidimitriou, D.
    Natl & Kapodistrian Univ Athens, Dept Phys, Sect Astrophys Astron & Mech, Athens 15784, Greece.;Natl Observ Athens, IAASARS, Penteli 15236, Greece..
    Held, E. , V
    INAF Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy.
    Jordi, C.
    Univ Barcelona IEEC UB, Inst Ciencies Cosmos ICCUB, Marti i Franques 1, Barcelona 08028, Spain..
    Paunzen, E.
    Masaryk Univ, Fac Sci, Dept Theoret Phys & Astrophys, Kotlarska 2, Brno 61137, Czech Republic..
    Spagna, A.
    INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy..
    Jackson, R. J.
    Keele Univ, Astrophys Grp, Keele ST55BG, Staffs, England..
    Maiz Apellaniz, J.
    Ctr Astrobiol CSIC INTA, Dept Astrofis, Campus ESAC,Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Asplund, M.
    Australian Acad Sci, Box 783, Canberra, ACT 2601, Australia..
    Bonifacio, P.
    Univ PSL, CNRS, Observ Paris, GEPI, 5 Pl Jules Janssen, F-92190 Meudon, France..
    Feltzing, S.
    Lund Observ, Dept Astron & Theoret Phys, Box 43, S-22100 Lund, Sweden..
    Binney, J.
    Clarendon Lab, Rudolf Peierls Ctr Theoret Phys, Parks Rd, Oxford OX1 3PU, England..
    Drew, J.
    UCL, Dept Phys & Astron, Gower St, London WC1E 6BT, England..
    Ferguson, A. M. N.
    Univ Edinburgh, Inst Astron, Blackford Hill, Edinburgh EH9 3HJ, Midlothian, Scotland..
    Micela, G.
    INAF Osservatorio Asron Palermo, Piazza Parlamento, I-190134 Palermo, Italy..
    Negueruela, I
    Univ Alicante, Dept Fis Aplicada, Fac Ciencias, Alicante 03690, Spain..
    Prusti, T.
    European Space Res & Technol Ctr ESTEC, European Space Agcy ESA, Keplerlaan 1, NL-2201 AZ Noordwijk, Netherlands..
    Rix, H-W
    Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany..
    Vallenari, A.
    INAF Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Bergemann, M.
    Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany.;Niels Bohr Inst, Niels Bohr Int Acad, Blegdamsvej 17, DK-2100 Copenhagen O, Denmark..
    Casey, A. R.
    Monash Univ, Sch Phys & Astron, Wellington Rd, Clayton, Vic 3800, Australia..
    de Laverny, P.
    Univ Cote dAzur, Lab Oratoire Lagrange, CNRS, Observ Cote dAzur, Bd Observ,CS 34229, F-34229 Nice, France..
    Frasca, A.
    INAF Osservatorio Astrofis Catania, Via S Sofia 78, I-95123 Catania, Italy..
    Hill, V
    Univ Cote dAzur, Lab Oratoire Lagrange, CNRS, Observ Cote dAzur, Bd Observ,CS 34229, F-34229 Nice, France..
    Lind, K.
    Stockholm Univ, AlbaNova Univ Ctr, Dept Astron, S-10691 Stockholm, Sweden..
    Sbordone, L.
    ESO European Org Astron Res Southern Hemisphere, Alonso de Cordova 3107, Casilla 19001, Santiago De Chi, Chile..
    Sousa, S. G.
    Univ Porto, Inst Astrofis & Ciencias Espaco, CAUP, Rua Estrelas, P-4150762 Porto, Portugal..
    Adibekyan, V
    Univ Porto, Inst Astrofis & Ciencias Espaco, CAUP, Rua Estrelas, P-4150762 Porto, Portugal..
    Caffau, E.
    Univ PSL, CNRS, Observ Paris, GEPI, 5 Pl Jules Janssen, F-92190 Meudon, France..
    Daflon, S.
    Observ Nacl MCTI ON, Rua Gal Jose Cristino 77, BR-20921400 Rio De Janeiro, Brazil..
    Feuillet, D. K.
    Lund Observ, Dept Astron & Theoret Phys, Box 43, S-22100 Lund, Sweden.;Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany..
    Gebran, M.
    St Marys Coll, Dept Chem & Phys, Notre Dame, IN 46556 USA..
    Gonzalez Hernandez, J. , I
    Inst Astrofis Canarias, Via Lactea S-N, Tenerife 38205, Spain.
    Guiglion, G.
    Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany..
    Herrero, A.
    Inst Astrofis Canarias, Via Lactea S-N, Tenerife 38205, Spain.;Univ La Laguna, Dept Astrofis, Tenerife 38205, Spain..
    Lobel, A.
    Rob Royal Observ Belgium, Ringlaan 3, B-1180 Brussels, Belgium..
    Montes, D.
    Univ Complutense Madrid, Fac Ciencias Fis, Dept Fis Tierra & Astrofis, Madrid 28040, Spain.;Univ Complutense Madrid, Fac Ciencias Fis, IPARCOS UCM Inst Fis Particulas & Cosmos, UCM, Madrid 28040, Spain..
    Morel, T.
    Univ Liege, Space Sci Technol & Astrophys Res STAR Inst, Bat B5c,Allee 6 Aout,19c, B-4000 Liege, Belgium..
    Ruchti, G.
    Lund Observ, Dept Astron & Theoret Phys, Box 43, S-22100 Lund, Sweden..
    Soubiran, C.
    Univ Bordeaux, Lab Astrophys Bordeaux, CNRS, B18N,Allee Geoffroy St Hilaire, F-33615 Pessac, France..
    Tabernero, H. M.
    Ctr Astrobiol CSIC INTA, Carretera Ajalvir Km 4, Madrid 28850, Spain..
    Tautvaisiene, G.
    Vilnius Univ, Inst Theoret Phys & Astron, Sauletekio Av 3, LT-10257 Vilnius, Lithuania..
    Traven, G.
    Univ Ljubljana, Fac Math & Phys, Jadranska 19, Ljubljana 1000, Slovenia..
    Valentini, M.
    Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany..
    Van der Swaelmen, M.
    INAF Osservatorio Astrofis Arcetri, Largo E Fermi 5, I-50125 Florence, Italy..
    Villanova, S.
    Univ Concepcion, Dept Astron, Casilla 160-C, Concepcion, Chile..
    Vazquez, C. Viscasillas
    Vilnius Univ, Inst Theoret Phys & Astron, Sauletekio Av 3, LT-10257 Vilnius, Lithuania..
    Bayo, A.
    Univ Valparaiso, Fac Ciencias, Inst Fis & Astron, Valparaiso, Chile.;Univ Valparaiso, Nucleo Milenio Formac Planetaria NPF, Valparaiso, Chile..
    Biazzo, K.
    INAF Osservatorio Astron Roma, Via Frascati 33, I-00040 Rome, Italy..
    Carraro, G.
    Univ Padua, Dept Phys & Astron, V Osservatorio 2, I-35122 Padua, Italy..
    Edvardsson, B.
    Uppsala Univ, Dept Phys & Astron, Theoret Astrophys, Box 516, S-75120 Uppsala, Sweden..
    Heiter, U.
    Uppsala Univ, Dept Phys & Astron, Div Astron & Space Phys, Observat Astrophys, Box 516, S-75120 Uppsala, Sweden..
    Jofre, P.
    Univ Diego Portales, Fac Ingn & Ciencias, Nucleo Astron, Av Ejercito 441, Santiago, Chile..
    Marconi, G.
    ESO European Org Astron Res Southern Hemisphere, Alonso de Cordova 3107, Casilla 19001, Santiago De Chi, Chile..
    Martayan, C.
    ESO European Org Astron Res Southern Hemisphere, Alonso de Cordova 3107, Casilla 19001, Santiago De Chi, Chile..
    Masseron, T.
    Inst Astrofis Canarias, Via Lactea S-N, Tenerife 38205, Spain.;Univ La Laguna, Dept Astrofis, Tenerife 38205, Spain..
    Monaco, L.
    Univ Andres Bello, Dept Ciencias Fis, Fernandez Concha 700, Santiago, Chile..
    Walton, N. A.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Zaggia, S.
    INAF Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Borsen-Koch, V. Aguirre
    Aarhus Univ, Stellar Astrophys Ctr, Dept Phys & Astron, Ny Munkegade 120, DK-8000 Aarhus C, Denmark..
    Alves, J.
    Univ Vienna, Dept Astrophys, Turkenschanzstr 17, A-1180 Vienna, Austria..
    Balaguer-Nunez, L.
    Univ Barcelona IEEC UB, Inst Ciencies Cosmos ICCUB, Marti i Franques 1, Barcelona 08028, Spain..
    Barklem, P. S.
    Uppsala Univ, Dept Phys & Astron, Theoret Astrophys, Box 516, S-75120 Uppsala, Sweden..
    Barrado, D.
    Ctr Astrobiol INTA CSIC, Camino Bajo del Castillos S-N, Madrid 28692, Spain..
    Bellazzini, M.
    INAF Osservatorio Astrofis & Sci Spazio, Via P Gobetti 93-3, I-40129 Bologna, Italy..
    Berlanas, S. R.
    Univ Alicante, Dept Fis Aplicada, Fac Ciencias, Alicante 03690, Spain..
    Binks, A. S.
    Keele Univ, Astrophys Grp, Keele ST55BG, Staffs, England.;MIT, Kavli Inst Astrophys & Space Res, 77 Massachusetts Ave, Cambridge, MA 02139 USA..
    Bressan, A.
    SISSA, Via Bonomea 265, I-34136 Trieste, Italy..
    Capuzzo-Dolcetta, R.
    Sapienza Univ Roma, Dept Phys, Rome, Italy..
    Casagrande, L.
    Australian Natl Univ, Res Sch Astron & Astrophys, Weston, ACT 2611, Australia..
    Casamiquela, L.
    Univ Bordeaux, Lab Astrophys Bordeaux, CNRS, B18N,Allee Geoffroy St Hilaire, F-33615 Pessac, France..
    Collins, R. S.
    Univ Edinburgh, Inst Astron, Royal Observ, Blackford Hill, Edinburgh EH9 3HJ, Midlothian, Scotland..
    D'Orazi, V
    INAF Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Dantas, M. L. L.
    Polish Acad Sci, Nicolaus Copernicus Astron Ctr, Ul Bartycka 18, PL-00716 Warsaw, Poland..
    Debattista, V. P.
    Univ Cent Lancashire, Jeremiah Horrocks Inst, Preston PR1 2HE, Lancs, England..
    Delgado-Mena, E.
    Univ Porto, Inst Astrofis & Ciencias Espaco, CAUP, Rua Estrelas, P-4150762 Porto, Portugal..
    Di Marcantonio, P.
    INAF Osservatorio Astron Trieste, Via GB Tiepolo 11, I-34143 Trieste, Italy..
    Drazdauskas, A.
    Vilnius Univ, Inst Theoret Phys & Astron, Sauletekio Av 3, LT-10257 Vilnius, Lithuania..
    Evans, N. W.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Famaey, B.
    Univ Strasbourg, CNRS, Observ Astron Strasbourg, UMR 7550, F-67000 Strasbourg, France..
    Franchini, M.
    INAF Osservatorio Astron Trieste, Via GB Tiepolo 11, I-34143 Trieste, Italy..
    Fremat, Y.
    Rob Royal Observ Belgium, Ringlaan 3, B-1180 Brussels, Belgium..
    Fu, X.
    Peking Univ, Kavli Inst Astron & Astrophys, Beijing 100871, Peoples R China..
    Geisler, D.
    Univ Concepcion, Dept Astron, Casilla 160-C, Concepcion, Chile.;Univ La Serena, Inst Invest Multidisciplinario Ciencia & Tecnol, Ave Raul Bitran S-N, La Serena, Chile.;Univ La Serena, Fac Ciencias, Dept Astron, Av Juan Cisternas 1200, La Serena, Chile..
    Gerhard, O.
    Max Planck Inst Ex Phys, Giessenbachstr 1, D-85748 Garching, Germany..
    Solares, E. A. Gonzalez
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Grebel, E. K.
    Heidelberg Univ, Zentrum Astron, Astron Rech Inst, Monchhofstr 12 14, D-69120 Heidelberg, Germany..
    Gutierrez Albarran, M. L.
    Univ Complutense Madrid, Fac Ciencias Fis, Dept Fis Tierra & Astrofis, Madrid 28040, Spain.;Univ Complutense Madrid, Fac Ciencias Fis, IPARCOS UCM Inst Fis Particulas & Cosmos, UCM, Madrid 28040, Spain..
    Jimenez-Esteban, F.
    Ctr Astrobiol CSIC INTA, Dept Astrofis, Campus ESAC,Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Jönsson, Henrik
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Khachaturyants, T.
    Univ Cent Lancashire, Jeremiah Horrocks Inst, Preston PR1 2HE, Lancs, England..
    Kordopatis, G.
    Univ Cote dAzur, Lab Oratoire Lagrange, CNRS, Observ Cote dAzur, Bd Observ,CS 34229, F-34229 Nice, France..
    Kos, J.
    Univ Ljubljana, Fac Math & Phys, Jadranska 19, Ljubljana 1000, Slovenia..
    Lagarde, N.
    Univ Bordeaux, Lab Astrophys Bordeaux, CNRS, B18N,Allee Geoffroy St Hilaire, F-33615 Pessac, France.;Univ Bourgogne Franche Comte, Inst UTINAM, OSU THETA Franche Comte Bourgogne, CNRS UMR6213,Observ Besancon, BP 1615, F-25010 Besancon, France..
    Ludwig, H-G
    Heidelberg Univ, Landessternwarte, Zentrum Astron, Konigstuhl 12, D-69117 Heidelberg, Germany..
    Mahy, L.
    Rob Royal Observ Belgium, Ringlaan 3, B-1180 Brussels, Belgium..
    Mapelli, M.
    INAF Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Marfil, E.
    Ctr Astrobiol CSIC INTA, Dept Astrofis, Campus ESAC,Camino Bajo del Castillo S-N, Madrid 28692, Spain..
    Martell, S. L.
    Univ New South Wales, Sch Phys, Sydney, NSW 2052, Australia..
    Messina, S.
    INAF Osservatorio Astrofis Catania, Via S Sofia 78, I-95123 Catania, Italy..
    Miglio, A.
    INAF Osservatorio Astrofis & Sci Spazio, Via P Gobetti 93-3, I-40129 Bologna, Italy.;Univ Bologna, Dipartimento Fis & Astron, Via Gobetti 93-2, I-40129 Bologna, Italy..
    Minchev, I
    Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany..
    Moitinho, A.
    Univ Lisbon, Fac Ciencias, CENTRA, Ed C8, P-1749016 Lisbon, Portugal..
    Montalban, J.
    Univ Bologna, Dipartimento Fis & Astron, Via Gobetti 93-2, I-40129 Bologna, Italy..
    Monteiro, M. J. P. F. G.
    Univ Porto, Inst Astrofis & Ciencias Espaco, CAUP, Rua Estrelas, P-4150762 Porto, Portugal.;Univ Porto, Dept Fis & Astron, Fac Ciencias, Porto, Portugal..
    Morossi, C.
    INAF Osservatorio Astron Trieste, Via GB Tiepolo 11, I-34143 Trieste, Italy..
    Mowlavi, N.
    Univ Geneva, Dept Astron, 51 Chemin Pegasi, CH-1290 Versoix, Switzerland..
    Mucciarelli, A.
    INAF Osservatorio Astrofis & Sci Spazio, Via P Gobetti 93-3, I-40129 Bologna, Italy.;Univ Bologna, Dipartimento Fis & Astron, Via Gobetti 93-2, I-40129 Bologna, Italy..
    Murphy, D. N. A.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Nardetto, N.
    Univ Cote dAzur, Lab Oratoire Lagrange, CNRS, Observ Cote dAzur, Bd Observ,CS 34229, F-34229 Nice, France..
    Ortolani, S.
    Univ Padua, Dept Phys & Astron, V Osservatorio 2, I-35122 Padua, Italy..
    Paletou, F.
    Univ Toulouse, Observ Midi Pyrenees, CNRS, IRAP, 14 Av E Belin, F-31400 Toulouse, France..
    Palous, J.
    CAS, Astron Inst, Bocni II 1401, Prague 14100 4, Czech Republic..
    Pickering, J. C.
    Imperial Coll London, Phys Dept, Prince Consort Rd, London SW7 2BZ, England..
    Quirrenbach, A.
    Heidelberg Univ, Landessternwarte, Zentrum Astron, Konigstuhl 12, D-69117 Heidelberg, Germany..
    Fiorentin, P. Re
    INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy..
    Read, J. , I
    Univ Surrey, Phys Dept, Guildford GU2 7XH, Surrey, England.
    Romano, D.
    INAF Osservatorio Astrofis & Sci Spazio, Via P Gobetti 93-3, I-40129 Bologna, Italy..
    Ryde, N.
    Lund Observ, Dept Astron & Theoret Phys, Box 43, S-22100 Lund, Sweden..
    Sanna, N.
    INAF Osservatorio Astrofis Arcetri, Largo E Fermi 5, I-50125 Florence, Italy..
    Santos, W.
    Observ Nacl MCTI ON, Rua Gal Jose Cristino 77, BR-20921400 Rio De Janeiro, Brazil..
    Seabroke, G. M.
    Univ Coll London, Mullard Space Sci Lab, Dorking RH5 6NT, Surrey, England..
    Spina, L.
    INAF Astron Observ Padua, Vicolo Osservatorio 5, I-35122 Padua, PD, Italy..
    Steinmetz, M.
    Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany..
    Stonkute, E.
    Vilnius Univ, Inst Theoret Phys & Astron, Astron Observ, Sauletekio Av 3, LT-10257 Vilnius, Lithuania..
    Sutorius, E.
    Univ Edinburgh, Inst Astron, Royal Observ, Blackford Hill, Edinburgh EH9 3HJ, Midlothian, Scotland..
    Thevenin, F.
    Univ Cote dAzur, Lab Oratoire Lagrange, CNRS, Observ Cote dAzur, Bd Observ,CS 34229, F-34229 Nice, France..
    Tosi, M.
    INAF Osservatorio Astrofis & Sci Spazio, Via P Gobetti 93-3, I-40129 Bologna, Italy..
    Tsantaki, M.
    INAF Osservatorio Astrofis Arcetri, Largo E Fermi 5, I-50125 Florence, Italy..
    Wright, N.
    Keele Univ, Astrophys Grp, Keele ST55BG, Staffs, England..
    Wyse, R. F. G.
    Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA..
    Zoccali, M.
    Pontificia Univ Catolica Chile, Inst Astrophys, Av Vicuna Mackenna 4860, Santiago, Chile..
    Zorec, J.
    Sorbonne Univ, CNRS, UPMC, UMR7095,Inst Astrophys Paris, 98Bis Bd Arago, F-75014 Paris, France..
    Zucker, D. B.
    Macquarie Univ, Dept Phys & Astron, Sydney, NSW 2109, Australia..
    The Gaia-ESO Public Spectroscopic Survey: Motivation, implementation, GIRAFFE data processing, analysis, and final data products star2022In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 666, article id A120Article in journal (Refereed)
    Abstract [en]

    Context. The Gaia-ESO Public Spectroscopic Survey is an ambitious project designed to obtain astrophysical parameters and elemental abundances for 100 000 stars, including large representative samples of the stellar populations in the Galaxy, and a well-defined sample of 60 (plus 20 archive) open clusters. We provide internally consistent results calibrated on benchmark stars and star clusters, extending across a very wide range of abundances and ages. This provides a legacy data set of intrinsic value, and equally a large wide-ranging dataset that is of value for the homogenisation of other and future stellar surveys and Gaia's astrophysical parameters. Aims. This article provides an overview of the survey methodology, the scientific aims, and the implementation, including a description of the data processing for the GIRAFFE spectra. A companion paper introduces the survey results. Methods. Gaia-ESO aspires to quantify both random and systematic contributions to measurement uncertainties. Thus, all available spectroscopic analysis techniques are utilised, each spectrum being analysed by up to several different analysis pipelines, with considerable effort being made to homogenise and calibrate the resulting parameters. We describe here the sequence of activities up to delivery of processed data products to the ESO Science Archive Facility for open use. Results. The Gaia-ESO Survey obtained 202 000 spectra of 115 000 stars using 340 allocated VLT nights between December 2011 and January 2018 from GIRAFFE and UVES. Conclusions. The full consistently reduced final data set of spectra was released through the ESO Science Archive Facility in late 2020, with the full astrophysical parameters sets following in 2022. A companion article reviews the survey implementation, scientific highlights, the open cluster survey, and data products.

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  • 15.
    Gurell, J.
    et al.
    Department of Physics, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden.
    Hartman, H.
    Lund Observatory, Lund University, Box 43, 22100 Lund, Sweden.
    Blackwell-Whitehead, R.
    Lund Observatory, Lund University, Box 43, 22100 Lund, Sweden.
    Nilsson, H.
    Lund Observatory, Lund University, Box 43, 22100 Lund, Sweden.
    Bäckström, E.
    Department of Physics, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden.
    Norlin, L. O.
    Department of Physics, Royal Institute of Technology, AlbaNova University Center, 10691 Stockholm, Sweden.
    Royen, P.
    Department of Physics, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden.
    Mannervik, S.
    Department of Physics, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden.
    The FERRUM project: transition probabilities for forbidden lines in [Fe II] and experimental metastable lifetimes2009In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 508, no 1, p. 525-529Article in journal (Refereed)
    Abstract [en]

    Context. Accurate transition probabilities for forbidden lines are important diagnostic parameters for low-density astrophysical plasmas. In this paper we present experimental atomic data for forbidden [Fe II] transitions that are observed as strong features in astrophysical spectra. Aims. We measure lifetimes for the 3d6 (3G)4sa4 and 3d 6 (3D)4sb4 D1/2 metastable levels in Fe II and experimental transition probabilities for the forbidden transitions 3d7a4F7/2,9/2-3d6( 3G)4sa4.Methods. The lifetimes were measured at the ion storage ring facility CRYRING using a laser probing technique. Astrophysical branching fractions were obtained from spectra of Eta Carinae, obtained with the Space Telescope Imaging Spectrograph onboard the Hubble Space Telescope. The lifetimes and branching fractions were combined to yield absolute transition probabilities.Results. The lifetimes of the a4G11/2 and the b4D1/2 levels have been measured and have the following values, r = 0.75 ± 0.10 s respectively. Furthermore, we have determined the transition probabilities for two forbidden transitions of a 4F7/2,9/2-a4G11/2 at 4243.97 and 4346.85Å. Both the lifetimes and the transition probabilities are compared to calculated values in the literature. 

  • 16.
    Gurell, J.
    et al.
    Department of Physics, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden.
    Nilsson, H.
    Lund Observatory, Lund University, Box 43, 22100 Lund, Sweden.
    Engström, L.
    Atomic Physics, Department of Physics, Lund University, Box 118, 22100 Lund, Sweden.
    Lundberg, H.
    Atomic Physics, Department of Physics, Lund University, Box 118, 22100 Lund, Sweden.
    Blackwell-Whitehead, R.
    Lund Observatory, Lund University, Box 43, 22100 Lund, Sweden.
    Nielsen, K. E.
    Catholic University of America, Washington, DC 20064, USA; Astrophysics Science Division, Code 667, Goddard Space Flight Center, Greenbelt, MD 20771, USA.
    Mannervik, S.
    Department of Physics, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden.
    The FERRUM project: laboratory-measured transition probabilities for Cr II2010In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 511, p. A68-A68Article in journal (Refereed)
    Abstract [en]

    Aims. We measure transition probabilities for Cr II transitions from the z 4HJ, z 2DJ, y 4FJ, and y 4GJ levels in the energy range 63 000 to 68 000 cm-1.Methods. Radiative lifetimes were measured using time-resolved laser-induced fluorescence from a laser-produced plasma. In addition, branching fractions were determined from intensity-calibrated spectra recorded with a UV Fourier transform spectrometer. The branching fractions and radiative lifetimes were combined to yield accurate transition probabilities and oscillator strengths.Results. We present laboratory measured transition probabilities for 145 Cr II lines and radiative lifetimes for 14 Cr II levels. The laboratory-measured transition probabilities are compared to the values from semi-empirical calculations and laboratory measurements in the literature.

  • 17.
    Gustafsson, Stefan
    et al.
    Malmö högskola, Faculty of Technology and Society (TS).
    Jönsson, Per
    Malmö högskola, Faculty of Technology and Society (TS).
    Fischer, C. Froese
    Grant, I. P.
    MCDHF and RCI calculations of energy levels, lifetimes and transition rates for 3l3l ', 3l4l ', and 3s5l states in Ca IX - As XXII and Kr XXV2017In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 597, no A76, article id A76Article in journal (Refereed)
    Abstract [en]

    Multiconfiguration Dirac-Hartree-Fock (MCDHF) calculations and relativistic configuration interaction (RCI) calculations were performed for states of the 3l3l 0, 3l4l 0 and 3s5l configurations in the Mg-like ions Ca IX - As XXII and KrXXV. Valence and core-valence electron correlation effects are accounted for through large configuration state function expansions. Calculated excitation energies are in very good agreement with observations for the lowest levels. For higher lying levels observations are often missing and present energies aid line identification in spectra. Lifetimes and transition data are given for all ions. There is an excellent agreement for both lifetimes and transition data with recent multiconfiguration Hartree-Fock Breit Pauli calculations.

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  • 18.
    Hansen, C.J.
    et al.
    European Southern Observatory (ESO), Karl-Schwarschild-Str. 2, 85748 Garching b. München, Germany; ‹.
    Primas, F.
    European Southern Observatory (ESO), Karl-Schwarschild-Str. 2, 85748 Garching b. München, Germany.
    Hartman, Henrik
    Malmö högskola, School of Technology (TS). Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, 22100 Lund, Sweden.
    Kratz, K.-L.
    Max-Planck-Institut für Chemie, Otto-Hahn-Institut, Joh.-J-Becherweg 27, 55128 Mainz, Germany.
    Wanajo, Shinya
    Technische Universität München, Excellence Cluster Universe, Boltzmannstr. 2, 85748 Garching, Germany; Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85748 Garching Germany; National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, 181-8588 Tokyo, Japan.
    Leibundgut, B.
    European Southern Observatory (ESO), Karl-Schwarschild-Str. 2, 85748 Garching b. München, Germany.
    Farouqi, K.
    Max-Planck-Institut für Chemie, Otto-Hahn-Institut, Joh.-J-Becherweg 27, 55128 Mainz, Germany; Landessternwarte Heidelberg (LSW, ZAH), Königstuhl 12, 69117 Heidelberg, Germany.
    Hallmann, O
    Max-Planck-Institut für Chemie, Otto-Hahn-Institut, Joh.-J-Becherweg 27, 55128 Mainz, Germany.
    Christlieb, N.
    Landessternwarte Heidelberg (LSW, ZAH), Königstuhl 12, 69117 Heidelberg, Germany.
    Nilsson, Hampus
    Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, 22100 Lund, Sweden.
    Silver and palladium help unveil the nature of a second r-process2012In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 545, no (A31), article id A31Article in journal (Refereed)
    Abstract [en]

    Context. The rapid neutron-capture process, which created about half of the heaviest elements in the solar system, is believed to have been unique. Many recent studies have shown that this uniqueness is not true for the formation of lighter elements, in particular those in the atomic number range 38 < Z < 48. Among these, palladium (Pd) and especially silver (Ag) are expected to be key indicators of a possible second r-process, but until recently they have been studied only in a few stars. We therefore target Pd and Ag in a large sample of stars and compare these abundances to those of Sr, Y, Zr, Ba, and Eu produced by the slow (s-) and rapid (r-) neutron-capture processes. Hereby we investigate the nature of the formation process of Ag and Pd. Aims. We study the abundances of seven elements (Sr, Y, Zr, Pd, Ag, Ba, and Eu) to gain insight into the formation process of the elements and explore in depth the nature of the second r-process. Methods. By adopting a homogeneous one-dimensional local thermodynamic equilibrium (1D LTE) analysis of 71 stars, we derive stellar abundances using the spectral synthesis code MOOG, and the MARCS model atmospheres. We calculate abundance ratio trends and compare the derived abundances to site-dependent yield predictions (low-mass O-Ne-Mg core-collapse supernovae and parametrised high-entropy winds), to extract characteristics of the second r-process. Results. The seven elements are tracers of different (neutron-capture) processes, which in turn allows us to constrain the formation process(es) of Pd and Ag. The abundance ratios of the heavy elements are found to be correlated and anti-correlated. These trends lead to clear indications that a second/weak r-process, is responsible for the formation of Pd and Ag. On the basis of the comparison to the model predictions, we find that the conditions under which this process takes place differ from those for the main r-process in needing lower neutron number densities, lower neutron-to-seed ratios, and lower entropies, and/or higher electron abundances. Conclusions. Our analysis confirms that Pd and Ag form via a rapid neutron-capture process that differs from the main r-process, the main and weak s-processes, and charged particle freeze-outs. We find that this process is efficiently working down to the lowest metallicity sampled by our analysis ([Fe/H] = −3.3). Our results may indicate that a combination of these explosive sites is needed to explain the variety in the observationally derived abundance patterns.

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  • 19.
    Hartman, Henrik
    et al.
    Malmö högskola, Faculty of Technology and Society (TS). Lund Observatory, Lund University, Box 43, 221 00 Lund, Sweden.
    Engström, Lars
    Department of Physics, Lund University, Box 118, 221 00 Lund, Sweden.
    Lundberg, Hans
    Lund Observatory, Lund University, Box 43, 221 00 Lund, Sweden; Department of Physics, Lund University, Box 118, 221 00 Lund, Sweden.
    Nilsson, Hampus
    Department of Physics, Lund University, Box 118, 221 00 Lund, Sweden.
    Quinet, Pascal
    Physique Atomique et Astrophysique, Université de Mons, 7000 Mons, Belgium; IPNAS, Université de Liège, 4000 Liège, Belgium.
    Fivet, Vanessa
    Physique Atomique et Astrophysique, Université de Mons, 7000 Mons, Belgium.
    Palmeri, Patrick
    Physique Atomique et Astrophysique, Université de Mons, 7000 Mons, Belgium.
    Malcheva, Galina
    Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee, 1784 Sofia, Bulgaria.
    Blagoev, Kiril
    Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee, 1784 Sofia, Bulgaria.
    Radiative data for highly excited 3d84d levels in Ni II from laboratory measurements and atomic calculations2017In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 600, article id A108Article in journal (Refereed)
    Abstract [en]

    Aims: This work reports new experimental radiative lifetimes and calculated oscillator strengths for transitions from 3d84d levels of astrophysical interest in singly ionized nickel. Methods: Radiative lifetimes of seven high-lying levels of even parity in Ni II (98 400-100 600 cm-1) have been measured using the time-resolved laser-induced fluorescence method. Two-step photon excitation of ions produced by laser ablation has been utilized to populate the levels. Theoretical calculations of the radiative lifetimes of the measured levels and transition probabilities from these levels are reported. The calculations have been performed using a pseudo-relativistic Hartree-Fock method, taking into account core polarization effects. Results: A new set of transition probabilities and oscillator strengths has been deduced for 477 Ni II transitions of astrophysical interest in the spectral range 194-520 nm depopulating even parity 3d84d levels. The new calculated gf-values are, on the average, about 20% higher than a previous calculation and yield lifetimes within 5% of the experimental values.

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  • 20.
    Hartman, Henrik
    et al.
    Malmö högskola, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM). Lund Observatory, Lund University.
    Nilsson, Hampus
    Lund Observatory, Lund University.
    Engström, L
    Department of Physics, Lund University.
    Lundberg, H
    Department of Physics, Lund University.
    The FERRUM project: Experimental lifetimes and transition probabilities from highly excited even 4d levels in Fe ii2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 584, no A24, article id A24Article in journal (Refereed)
    Abstract [en]

    We report lifetime measurements of the 6 levels in the 3d6(5D)4d e6G term in Fe ii at an energy of 10.4 eV, and f -values for 14 transitions from the investigated levels. The lifetimes were measured using time-resolved laser-induced fluorescence on ions in a laserproduced plasma. The high excitation energy, and the fact that the levels have the same parity as the the low-lying states directly populated in the plasma, necessitated the use of a two-photon excitation scheme. The probability for this process is greatly enhanced by the presence of the 3d6(5D)4p z6F levels at roughly half the energy di erence. The f -values are obtained by combining the experimental lifetimes with branching fractions derived using relative intensities from a hollow cathode discharge lamp recorded with a Fourier transform spectrometer. The data is important for benchmarking atomic calculations of astrophysically important quantities and useful for spectroscopy of hot stars.

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  • 21.
    Heiter, U.
    et al.
    Observational Astrophysics, Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala, 75120, Sweden.
    Lind, K.
    Department of Astronomy, Stockholm University, AlbaNova, Roslagstullbacken 21, Stockholm, 10691, Sweden.
    Bergemann, M.
    Max-Planck Institut für Astronomie (MPIA), Königstuhl 17, Heidelberg, 69117, Germany.
    Asplund, M.
    Research School of Astronomy and Astrophysics, Australian National University, Cotter Road, Weston Creek, 2611, ACT, Australia.
    Mikolaitis, S.
    Institute of Theoretical Physics and Astronomy, Vilnius University, Saulėtekio av. 3, Vilnius, 10257, Lithuania.
    Barklem, P. S.
    Observational Astrophysics, Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala, 75120, Sweden.
    Masseron, T.
    Instituto de Astrofísica de Canarias, La Laguna, Tenerife, 38205, Spain; Departamento de Astrofísica, Universidad de la Laguna, La Laguna, Tenerife, 38206, Spain.
    de Laverny, P.
    Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Blvd de l'Observatoire, Nice, 06304, France.
    Magrini, L.
    INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, Florence, 50125, Italy.
    Edvardsson, B.
    Observational Astrophysics, Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala, 75120, Sweden.
    Jönsson, H.
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM). Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, Lund, 22100, Sweden.
    Pickering, J. C.
    Blackett Laboratory, Imperial College London, London, SW72BW, United Kingdom.
    Ryde, N.
    Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, Lund, 22100, Sweden.
    Aran, A. Bayo
    Instituto de Física y Astronomiá, Facultad de Ciencias, Universidad de Valparaíso, Av. Gran Bretanã 1111, Casilla, Valparaíso, 5030, Chile; Núcleo Milenio de Formación Planetaria-NPF, Universidad de Valparaíso, Av. Gran Bretanã 1111, Valparaíso, Chile.
    Bensby, T.
    Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, Lund, 22100, Sweden.
    Casey, A. R.
    Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB30HA, United Kingdom; School of Physics and Astronomy, Monash University, Wellington Rd, Clayton, 3800, VIC, Australia; Center of Excellence for Astrophysics in Three Dimensions (ASTRO-3D), Australia.
    Feltzing, S.
    Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, Lund, 22100, Sweden.
    Jofre, P.
    Núcleo de Astronomiá, Facultad de Ingenieriá, Universidad Diego Portales, Av. Ejército 441, Santiago, Chile.
    Korn, A. J.
    Observational Astrophysics, Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala, 75120, Sweden.
    Pancino, E.
    INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, Florence, 50125, Italy; Space Science Data Center, Agenzia Spaziale Italiana, Via del Politecnico, s.n.c., Roma, 00133, Italy.
    Damiani, F.
    INAF, Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, Palermo, 90134, Italy.
    Lanzafame, A.
    Dipartimento di Fisica e Astronomia, Sezione Astrofisica, Universitá di Catania, Via S. Sofia 78, Catania, 95123, Italy.
    Lardo, C.
    Laboratoire d'Astrophysique, Ecole Polytechnique Fédérale de Lausanne (EPFL), Observatoire de Sauverny, Versoix, 1290, Switzerland.
    Monaco, L.
    Departamento de Ciencias Fisicas, Universidad Andres Bello, Fernandez Concha 700, Las Condes, Santiago, Chile.
    Morbidelli, L.
    INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, Florence, 50125, Italy.
    Smiljanic, R.
    Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, ul. Bartycka 18, Warsaw, 00-716, Poland.
    Worley, C.
    Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB30HA, United Kingdom.
    Zaggia, S.
    INAF-Padova Observatory, Vicolo dell'Osservatorio 5, Padova, 35122, Italy.
    Randich, S.
    INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, Florence, 50125, Italy.
    Gilmore, G. F.
    Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB30HA, United Kingdom.
    Atomic data for the Gaia-ESO Survey2021In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 645, article id A106Article in journal (Refereed)
    Abstract [en]

    Context. We describe the atomic and molecular data that were used for the abundance analyses of FGK-type stars carried out within the Gaia-ESO Public Spectroscopic Survey in the years 2012 to 2019. The Gaia-ESO Survey is one among several current and future stellar spectroscopic surveys producing abundances for Milky-Way stars on an industrial scale.Aims. We present an unprecedented effort to create a homogeneous common line list, which was used by several abundance analysis groups using different radiative transfer codes to calculate synthetic spectra and equivalent widths. The atomic data are accompanied by quality indicators and detailed references to the sources. The atomic and molecular data are made publicly available at the CDS.Methods. In general, experimental transition probabilities were preferred but theoretical values were also used. Astrophysical gf-values were avoided due to the model-dependence of such a procedure. For elements whose lines are significantly affected by a hyperfine structure or isotopic splitting, a concerted effort has been made to collate the necessary data for the individual line components. Synthetic stellar spectra calculated for the Sun and Arcturus were used to assess the blending properties of the lines. We also performed adetailed investigation of available data for line broadening due to collisions with neutral hydrogen atoms.Results. Among a subset of over 1300 lines of 35 elements in the wavelength ranges from 475 to 685 nm and from 850 to 895 nm, we identified about 200 lines of 24 species which have accurate gf-values and are free of blends in the spectra of the Sun and Arcturus. For the broadening due to collisions with neutral hydrogen, we recommend data based on Anstee-Barklem-O'Mara theory, where possible. We recommend avoiding lines of neutral species for which these are not available. Theoretical broadening data by R.L. Kurucz should be used for ScII, TiII, and YII lines; additionally, for ionised rare-earth species, the Unsold approximation with an enhancement factor of 1.5 for the line width can be used.Conclusions. The line list has proven to be a useful tool for abundance determinations based on the spectra obtained within the Gaia-ESO Survey, as well as other spectroscopic projects. Accuracies below 0.2 dex are regularly achieved, where part of the uncertainties are due to differences in the employed analysis methods. Desirable improvements in atomic data were identified for a number of species, most importantly AlI, SI, and CrII, but also NaI, SiI, CaII, and NiI.

  • 22.
    Ivarsson, S.
    et al.
    Atomic Astrophysics, Lund Observatory, Lund University, PO Box 43, 22100 Lund, Sweden.
    Andersen, J.
    Astronomical Observatory, Niels Bohr Institute for Astronomy, Physics & Geophysics, Juliane Maries Vej 30, 2100 Copenhagen, Denmark; Nordic Optical Telescope Scientific Association, La Palma, Canary Islands, Spain.
    Nordström, B.
    Atomic Astrophysics, Lund Observatory, Lund University, PO Box 43, 22100 Lund, Sweden; Astronomical Observatory, Niels Bohr Institute for Astronomy, Physics & Geophysics, Juliane Maries Vej 30, 2100 Copenhagen, Denmark.
    Dai, X.
    Atomic Physics, Department of Physics, Lund Institute of Technology, PO Box 118, 22100 Lund, Sweden.
    Johansson, S.
    Atomic Astrophysics, Lund Observatory, Lund University, PO Box 43, 22100 Lund, Sweden.
    Lundberg, H.
    Atomic Physics, Department of Physics, Lund Institute of Technology, PO Box 118, 22100 Lund, Sweden.
    Nilsson, H.
    Atomic Astrophysics, Lund Observatory, Lund University, PO Box 43, 22100 Lund, Sweden.
    Hill, V.
    GEPI, Observatoire de Paris-Meudon (UMR 8111), DASGAL, 2 pl. Jules Janssen, 92195 Meudon Cedex, France.
    Lundqvist, M.
    Atomic Astrophysics, Lund Observatory, Lund University, PO Box 43, 22100 Lund, Sweden.
    Wyart, J. F.
    Laboratoire Aimé Cotton, Centre National de la Recherche Scientifique, Orsay, France.
    Improved oscillator strengths and wavelengths for Os I and Ir I, and new results on earlyr-process nucleosynthesis2003In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 409, no 3, p. 1141-1149Article in journal (Refereed)
    Abstract [en]

    The radioactive decay of 238U and 232Th has recently been used to determine ages for some of the oldest stars in the Universe. This has highlighted the need for accurate observational constraints on production models for the heaviest r-process elements which might serve as stable references, notably osmium and iridium. In order to provide a firmer basis for the observed abundances, we have performed laser-induced fluorescence measurements and Fourier Transform Spectroscopy to determine new radiative lifetimes and branching fractions for selected levels in Os I and Ir I. From these data, we determine new absolute oscillator strengths and improved wavelengths for 18 Os I and 4 Ir I lines. A reanalysis of VLT spectra of CS 31082-001 and new results for other stars with Os and Ir detections show that (i): the lines in the UV and λ 4260 Å yield reliable Os abundances, while those at   4135, 4420 Å are heavily affected by blending; (ii): the Os and Ir abundances are identical in all the stars; (iii): the heavy-element abundances in very metal-poor stars conform closely to the scaled solar r-process pattern throughout the range 56 ≤ Z ≤ 77; and (iv): neither Os or Ir nor any lighter species are suitable as reference elements for the radioactive decay of Th and U.

     

  • 23.
    Jönsson, H.
    et al.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, S-22100 Lund, Sweden..
    Ryde, N.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, S-22100 Lund, Sweden..
    Harper, G. M.
    Univ Dublin Trinity Coll, Sch Phys, Dublin 2, Ireland..
    Cunha, K.
    Observ Nacl, BR-20921400 Rio De Janeiro, RJ, Brazil..
    Schultheis, M.
    Observ Cote Azur, F-06304 Nice 4, France..
    Eriksson, K.
    Uppsala Univ, Dept Phys & Astron, S-75120 Uppsala, Sweden..
    Kobayashi, C.
    Univ Hertfordshire, Ctr Astrophys Res, Hatfield AL10 9AB, Herts, England..
    Smith, V. V.
    Natl Opt Astron Observ, Tucson, AZ 85719 USA..
    Zoccali, M.
    Pontificia Univ Catolica Chile, Inst Astrofis, Santiago 22, Chile..
    Chemical evolution of fluorine in the bulge High-resolution K-band spectra of giants in three fields2014In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 564, article id A122Article in journal (Refereed)
    Abstract [en]

    Context. Possible main formation sites of fluorine in the Universe include asymptotic giant branch (AGB) stars, the v-process in Type II supernova, and/or Wolf-Rayet stars. The importance of the Wolf-Rayet stars has theoretically been questioned and they are probably not needed in modeling the chemical evolution of fluorine in the solar neighborhood. It has, however, been suggested that Wolf-Rayet stars are indeed needed to explain the chemical evolution of fluorine in the bulge. The molecular spectral data, needed to determine the fluorine abundance, of the often used HF-molecule has not been presented in a complete and consistent way and has recently been debated in the literature. Aims. We intend to determine the trend of the fluorine-oxygen abundance ratio as a function of a metallicity indicator in the bulge to investigate the possible contribution from Wolf-Rayet stars. Additionally, we present here a consistent HF line list for the K- and L-bands including the often used 23 358.33 angstrom line. Methods. High-resolution near-infrared spectra of eight K giants were recorded using the spectrograph CRIRES mounted at the VLT. A standard setting was used that covered the HF molecular line at 23 358.33 angstrom. The fluorine abundances were determined using spectral fitting. We also re-analyzed five previously published bulge giants observed with the Phoenix spectrograph on Gemini using our new HF molecular data. Results. We find that the fluorine-oxygen abundance in the bulge probably cannot be explained with chemical evolution models that only include AGB stars and the v-process in supernovae Type II, that is a significant amount of fluorine production in Wolf-Rayet stars is most likely needed to explain the fluorine abundance in the bulge. For the HF line data, we find that a possible reason for the inconsistencies in the literature, where two different excitation energies were used, is two different definitions of the zero-point energy for the HF molecule and therefore also two accompanying different dissociation energies. Both line lists are correct as long as the corresponding consistent partition function is used in the spectral synthesis. However, we suspect this has not been the case in several earlier works, which led to fluorine abundances similar to 0.3 dex too high. We present a line list for the K- and L-bands and an accompanying partition function.

  • 24.
    Jönsson, H.
    et al.
    Department of Astronomy and Theoretical Physics Lund Observatory, Lund University, Box 43, 221 00 Lund, Sweden.
    Ryde, N.
    Department of Astronomy and Theoretical Physics Lund Observatory, Lund University, Box 43, 221 00 Lund, Sweden.
    Nissen, P. E.
    Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark.
    Collet, R.
    Max Planck Institute for Astrophysics, Karl-Schwarzschild-Strasse 1, Postfach 1317, 857 41 Garching bei München, Germany.
    Eriksson, K.
    Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden.
    Asplund, M.
    Max Planck Institute for Astrophysics, Karl-Schwarzschild-Strasse 1, Postfach 1317, 857 41 Garching bei München, Germany.
    Gustafsson, B.
    Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden.
    Sulphur abundances in halo giants from the [S ı] line at 1082 nm and the S ı triplet around 1045 nm2011In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 530, p. A144-A144Article in journal (Refereed)
    Abstract [en]

    Context. It is still debated whether or not the Galactic chemical evolution of sulphur in the halo follows the flat trend with [Fe/H] that is ascribed to the result of explosive nucleosynthesis in type II SNe. It has been suggested that the disagreement between different investigations of sulphur abundances in halo stars might be owing to problems with the diagnostics used, that a new production source of sulphur might be needed in the early Universe, like hypernovae, or that the deposition of supernova ejecta into the interstellar medium is time-delayed.

    Aims. The aim of this study is to try to clarify this situation by measuring the sulphur abundance in a sample of halo giants using two diagnostics: the S I triplet around 1045 nm and the [S I] line at 1082 nm. The latter of the two is not believed to be sensitive to non-LTE effects. We can thereby minimize the uncertainties in the diagnostic used and estimate the usefulness of the triplet for the sulphur determination in halo K giants. We will also be able to compare our sulphur abundance differences from the two diagnostics with the expected non-LTE effects in the 1045 nm triplet previously calculated by others.

    Methods. High-resolution near-infrared spectra of ten K giants were recorded using the spectrometer CRIRES mounted at VLT. Two standard settings were used, one covering the S I triplet and one covering the [S I] line. The sulphur abundances were individually determined with equivalent widths and synthetic spectra for the two diagnostics using tailored 1D model atmospheres and relying on non-LTE corrections from the litterature. Effects of convective inhomogeneities in the stellar atmospheres are investigated.

    Results. The sulphur abundances derived from both the [S I] line and the non-LTE corrected 1045 nm triplet favor a flat trend for the evolution of sulphur. In contrast to some previous studies, we saw no “high” values of [S/Fe] in our sample.

    Conclusions. We corroborate the flat trend in the [S/Fe] vs. [Fe/H] plot for halo stars found in some previous studies but do not find a scatter or a rise in [S/Fe] as obtained in other works. We find the sulphur abundances deduced from the non-LTE corrected triplet to be somewhat lower than the abundances from the [S I] line, possibly indicating too large non-LTE corrections. Considering 3D modeling, however, they might instead be too small. Moreover, we show that the [S I] line can be used as a sulphur diagnostic down to [Fe/H]  ~  −2.3 in giants.

  • 25.
    Jönsson, H.
    et al.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden.;IAC, Tenerife 38205, Spain.;Univ La Laguna, Dept Astrofis, E-38206 Tenerife, Spain..
    Ryde, N.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden..
    Schultheis, M.
    Observ Cote Azur, Blvd Observ,BP 4229, F-06304 Nice 4, France..
    Zoccali, M.
    Pontificia Univ Catolica Chile, Inst Astrofis, Av Vicuna Mackenna 4860, Santiago 7820436, Chile.;Millennium Inst Astrophys, Av Vicuna Mackenna 4860, Santiago 7820436, Chile..
    Abundances of disk and bulge giants from high-resolution optical spectra II. O, Mg, Co, and Ti in the bulge sample2017In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 598, article id A101Article in journal (Refereed)
    Abstract [en]

    Context. Determining elemental abundances of bulge stars can, via chemical evolution modeling, help to understand the formation and evolution of the bulge. Recently there have been claims both for and against the bulge having a different [alpha/Fe] versus [Fe/H] trend as compared to the local thick disk. This could possibly indicate a faster, or at least different, formation timescale of the bulge as compared to the local thick disk. Aims. We aim to determine the abundances of oxygen, magnesium, calcium, and titanium in a sample of 46 bulge K giants, 35 of which have been analyzed for oxygen and magnesium in previous works, and compare this sample to homogeneously determined elemental abundances of a local disk sample of 291 K giants. Methods. We used spectral synthesis to determine both the stellar parameters and elemental abundances of the bulge stars analyzed here. We used the exact same method that we used to analyze the comparison sample of 291 local K giants in Paper I of this series. Results. Compared to the previous analysis of the 35 stars in our sample, we find lower [Mg/Fe] for [Fe/H] > -0.5, and therefore contradict the conclusion about a declining [O/Mg] for increasing [Fe/H]. We instead see a constant [O/Mg] over all the observed [Fe/H] in the bulge. Furthermore, we find no evidence for a different behavior of the alpha-iron trends in the bulge as compared to the local thick disk from our two samples.

  • 26.
    Jönsson, Henrik
    et al.
    Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, 221 00 Lund, Sweden; Instituto de Astrofísica de Canarias (IAC), 38205 La Laguna, Tenerife, Spain; Universidad de La Laguna, Dpto. Astrofísica, 38206 La Laguna, Tenerife, Spain.
    Ryde, Nils
    Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, 221 00 Lund, Sweden.
    Nordlander, T
    Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden.
    Pehlivan Rhodin, Asli
    Malmö högskola, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM). Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, 221 00 Lund, Sweden.
    Hartman, Henrik
    Malmö högskola, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM). Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, 221 00 Lund, Sweden.
    Jönsson, Per
    Malmö högskola, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Eriksson, Kjell
    Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden.
    Abundances of disk and bulge giants from high-resolution optical spectra: I. O, Mg, Ca, and Ti in the solar neighborhood and Kepler field samples2017In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 598, article id A100Article in journal (Refereed)
    Abstract [en]

    Context. The Galactic bulge is an intriguing and significant part of our Galaxy, but it is hard to observe because it is both distant and covered by dust in the disk. Therefore, there are not many high-resolution optical spectra of bulge stars with large wavelength coverage, whose determined abundances can be compared with nearby, similarly analyzed stellar samples. Aims. We aim to determine the diagnostically important alpha elements of a sample of bulge giants using high-resolution optical spectra with large wavelength coverage. The abundances found are compared to similarly derived abundances from similar spectra of similar stars in the local thin and thick disks. In this first paper we focus on the solar neighborhood reference sample. Methods. We used spectral synthesis to derive the stellar parameters as well as the elemental abundances of both the local and bulge samples of giants. We took special care to benchmark our method of determining stellar parameters against independent measurements of effective temperatures from angular diameter measurements and surface gravities from asteroseismology. Results. In this first paper we present the method used to determine the stellar parameters and elemental abundances, evaluate them, and present the results for our local disk sample of 291 giants. Conclusions. When comparing our determined spectroscopic temperatures to those derived from angular diameter measurements, we reproduce these with a systematic difference of +10 K and a standard deviation of 53 K. The spectroscopic gravities reproduce those determined from asteroseismology with a systematic offset of +0.10 dex and a standard deviation of 0.12 dex. When it comes to the abundance trends, our sample of local disk giants closely follows trends found in other works analyzing solar neighborhood dwarfs, showing that the much brighter giant stars are as good abundance probes as the often used dwarfs.

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  • 27.
    Jönsson, Per
    et al.
    Malmö högskola, School of Technology (TS).
    Ekman, Jörgen
    Malmö högskola, School of Technology (TS).
    Gustafsson, Stefan
    Malmö högskola, School of Technology (TS).
    Hartman, Henrik
    Malmö högskola, School of Technology (TS).
    Karlsson, Lennart
    Malmö högskola, School of Technology (TS).
    du Rietz, Rickard
    Malmö högskola, School of Technology (TS).
    Gaigalas, Gediminas
    Godefroid, Michel
    Froese Fischer, Charlotte
    Energy levels and transition rates for the boron isoelectronic sequence: Si X, Ti XVIII – Cu XXV2013In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 559, article id A100Article in journal (Refereed)
    Abstract [en]

    Relativistic configuration interaction (RCI) calculations are performed for 291 states belonging to the configurations 1s22s22p, 1s22s2p2, 1s22p3, 1s22s23l, 1s22s2p3l, 1s22p23l, 1s22s24l , 1s22s2p4l , and 1s22p24l (l = 0, 1,2 and l = 0, 1, 2, 3) in boron-like ions Si X and Ti XVIII to Cu XXV. Electron correlation effects are represented in the wave functions by large configuration state function (CSF) expansions. States are transformed from j j-coupling to LS -coupling, and the LS -percentage compositions are used for labeling the levels. Radiative electric dipole transition rates are given for all ions, leading to massive data sets. Calculated energy levels are compared with other theoretical predictions and crosschecked against the Chianti database, NIST recommended values, and other observations. The accuracy of the calculations are high enough to facilitate the identification of observed spectral lines.

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  • 28.
    Jönsson, Per
    et al.
    Malmö högskola, Faculty of Technology and Society (TS).
    Radziute, Laima
    Gaigalas, Gediminas
    Godefroid, Michel
    Marques, Jose
    Brage, Tomas
    Froese Fischer, Charlotte
    Grant, Ian
    Accurate multiconfiguration calculations of energy levels, lifetimes and transition rates for the silicon isoelectronic sequence: Ti IX - Ge XIX, Sr XXV, Zr XXVII, Mo XXIX2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 585, article id A26Article in journal (Refereed)
    Abstract [en]

    Multiconfiguration Dirac-Hartree-Fock (MCDHF) calculations and relativistic configuration interaction (RCI) calculations are performed for states of the 3s23p2, 3s3p3 and 3s23p3d configurations in the Si-like ions Ti IX – Ge XIX, Sr XXV, Zr XXVII and Mo XXIX. Valence and core-valence electron correlation e ects are accounted for through large configuration state function expansions. Calculated energy levels are compared with data from other calculations and with experimental data from the reference databases. Lifetime and transition rates along with uncertainty estimations are given for all ions. Energies from the calculations are in excellent agreement with observations and computed wavelength are almost of spectroscopic accuracy, aiding line identification in spectra.

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  • 29.
    Li, W.
    et al.
    Chinese Acad Sci, Natl Astron Observ, Beijing 100012, Peoples R China..
    Jönsson, P.
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Amarsi, A. M.
    Uppsala Univ, Dept Phys & Astron, Theoret Astrophys, Box 516, S-75120 Uppsala, Sweden..
    Li, M. C.
    Huizhou Univ, Sch Elect Informat & Elect Engn, Huizhou 516007, Peoples R China..
    Grumer, J.
    Uppsala Univ, Dept Phys & Astron, Theoret Astrophys, Box 516, S-75120 Uppsala, Sweden..
    Extended atomic data for oxygen abundance analyses2023In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 674, article id A54Article in journal (Refereed)
    Abstract [en]

    As the most abundant element in the universe after hydrogen and helium, oxygen plays a key role in planetary, stellar, and galactic astrophysics. Its abundance is especially influential in terms of stellar structure and evolution, and as the dominant opacity contributor at the base of the Sun's convection zone, it is central to the discussion on the solar modelling problem. However, abundance analyses require complete and reliable sets of atomic data. We present extensive atomic data for O I by using the multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction methods. We provide the lifetimes and transition probabilities for radiative electric dipole transitions and we compare them with results from previous calculations and available measurements. The accuracy of the computed transition rates is evaluated by the differences between the transition rates in Babushkin and Coulomb gauges, as well as via a cancellation factor analysis. Out of the 989 computed transitions in this work, 205 are assigned to the accuracy classes AA-B, that is, with uncertainties smaller than 10%, following the criteria defined by the Atomic Spectra Database from the National Institute of Standards and Technology. We discuss the influence of the new log(gf) values on the solar oxygen abundance, ultimately advocating for log epsilon(O) = 8.70 +/- 0.04.

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  • 30.
    Li, Wenxian
    et al.
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Hartman, Henrik
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Wang, Kai
    Hebei Key Lab of Optic-electronic Information and Materials, The College of Physics Science and Technology, Hebei University,.
    Jönsson, Per
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Theoretical investigation of oscillator strengths and lifetimes inTi ii2020In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 643, p. 1-14, article id A156Article in journal (Refereed)
    Abstract [en]

    Aims. Accurate atomic data for Ti II are essential for abundance analyses in astronomical objects. The aim of this work is to provide accurate and extensive results of oscillator strengths and lifetimes for Ti II.

    Methods. The multiconfiguration Dirac–Hartree–Fock and relativistic configuration interaction (RCI) methods, which are implemented in the general-purpose relativistic atomic structure package GRASP2018, were used in the present work. In the final RCI calculations, the transverse-photon (Breit) interaction, the vacuum polarisation, and the self-energy corrections were included.

    Results. Energy levels and transition data were calculated for the 99 lowest states in Ti II. Calculated excitation energies are found to be in good agreement with experimental data from the Atomic Spectra Database of the National Institute of Standards and Technology based on the study by Huldt et al. Lifetimes and transition data, for example, line strengths, weighted oscillator strengths, and transition probabilities for radiative electric dipole (E1), magnetic dipole (M1), and electric quadrupole (E2) transitions, are given and extensively compared with the results from previous calculations and measurements, when available. The present theoretical results of the oscillator strengths are, overall, in better agreement with values from the experiments than the other theoretical predictions. The computed lifetimes of the odd states are in excellent agreement with the measured lifetimes. Finally, we suggest a relabelling of the 3d2(12D)4p y2 D3/2o and z2 P3/2o levels.

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  • 31.
    Li, Wenxian
    et al.
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Rynkun, P.
    Radziute, L.
    Gaigalas, G.
    Atalay, B.
    Papoulia, Asimina
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Wang, K.
    Hartman, Henrik
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Ekman, Jörgen
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Brage, T.
    Chen, C. Y.
    Jönsson, Per
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Multiconfiguration Dirac-Hartree-Fock calculations of Lande g-factors for ions of astrophysical interest: B II, C I-IV, Al I-II, Si I-IV, P II, S II, Cl III, Ar IV, Ca I, Ti II, Zr III, and Sn II2020In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 639, article id A25Article in journal (Refereed)
    Abstract [en]

    Aims. The Lande g-factor is an important parameter in astrophysical spectropolarimetry, used to characterize the response of a line to a given value of the magnetic field. The purpose of this paper is to present accurate Lande g-factors for states in B II, C I-IV, Al I-II, Si I-IV, P II, S II, Cl III, Ar IV, Ca I, Ti II, Zr III, and Sn II.Methods. The multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction methods, which are implemented in the general-purpose relativistic atomic structure package GRASP2K, are employed in the present work to compute the Lande g-factors for states in B II, C I-IV, Al I-II, Si I-IV, P II, S II, Cl III, Ar IV, Ca I, Ti II, Zr III, and Sn II. The accuracy of the wave functions for the states, and thus the accuracy of the resulting Lande g-factors, is evaluated by comparing the computed excitation energies and energy separations with the National Institute of Standards and Technology (NIST) recommended data.Results. All excitation energies are in very good agreement with the NIST values except for Ti II, which has an average difference of 1.06%. The average uncertainty of the energy separations is well below 1% except for the even states of Al I; odd states of Si I, Ca I, Ti II, Zr III; and even states of Sn II for which the relative differences range between 1% and 2%. Comparisons of the computed Lande g-factors are made with available NIST data and experimental values. Analysing the LS-composition of the wave functions, we quantify the departures from LS-coupling and summarize the states for which there is a difference of more than 10% between the computed Lande g-factor and the Lande g-factor in pure LS-coupling. Finally, we compare the computed Lande g-factors with values from the Kurucz database.

  • 32.
    Ljung, G.
    et al.
    Atomic Astrophysics, Lund Observatory, Box 43, 221 00 Lund, Sweden.
    Nilsson, H.
    Atomic Astrophysics, Lund Observatory, Box 43, 221 00 Lund, Sweden.
    Asplund, M.
    Research School of Astronomy and Astrophysics, Australian National University, Mt. Stromlo Observatory, Cotter Rd., Weston, ACT 2611, Australia.
    Johansson, S.
    Atomic Astrophysics, Lund Observatory, Box 43, 221 00 Lund, Sweden.
    New and improved experimental oscillator strengths in Zr II and the solar abundance of zirconium2006In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 456, no 3, p. 1181-1185Article in journal (Refereed)
    Abstract [en]

    Using the Fourier Transform Spectrometer at Lund Observatory, intensity calibrated spectra of singly ionized zirconium have been recorded and analyzed. Oscillator strengths for 263 Zr II spectral lines in the region 2500-5400 A have been derived by combining new experimental branching fractions with previously measured radiative lifetimes. The transitions combine 34 odd parity levels with 29 low metastable levels between 0 and 2.4 eV. The experimental branching fractions have been compared with theoretical values and the oscillator strengths with previously published data when available. The oscillator strengths have been employed to derive the solar photospheric Zr abundance based on both ID and 3D model atmospheres. Based on the seven best and least perturbed Zr II lines in the solar disk-center spectrum, we determine the solar Zr abundance to log εZr = 2.58 ±0.02 when using a 3D hydrodynamical solar model atmosphere. The new value is in excellent agreement with the meteoritic Zr abundance. © ESO 2006.

  • 33.
    Lomaeva, M.
    et al.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden..
    Jönsson, H.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden..
    Ryde, N.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden..
    Schultheis, M.
    Observ Cote Azur, Blvd Observ,BP 4229, F-06304 Nice 4, France..
    Thorsbro, B.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden..
    Abundances of disk and bulge giants from high-resolution optical spectra III. Sc, V, Cr, Mn, Co, Ni2019In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 625, article id A141Article in journal (Refereed)
    Abstract [en]

    Context. The formation and evolution of the Galactic bulge and the Milky Way is still a debated subject. Observations of the X-shaped bulge, cylindrical stellar motions, and the presumed existence of a fraction of young stars in the bulge have suggested that it formed through secular evolution of the disk and not through gas dissipation and/or mergers, as thought previously. Aims. Our goal was to measure the abundances of six iron-peak elements (Sc, V, Cr, Mn, Co, and Ni) in the local thin and thick disks and in the bulge. These abundances can provide additional observational constraints for Galaxy formation and chemical evolution models, and help us to understand whether the bulge has emerged from the thick disk or not. Methods. We use high-resolution optical spectra of 291 K giants in the local disk mostly obtained by the FIES at NOT (signal-tonoise ratio (S/N) of 80-100) and 45 K giants in the bulge obtained by the UVES/FLAMES at VLT (S/N of 10-80). The abundances are measured using Spectroscopy Made Easy (SME). Additionally, we apply non-local thermodynamic equilibrium corrections to the ratios [Mn/Fe] and [Co/Fe]. The thin and thick disks were separated according to their metallicity, [Ti/Fe], as well as proper motions and the radial velocities from Gaia DR2. Results. The trend of [V/Fe] vs. [Fe/H] shows a separation between the disk components, being more enhanced in the thick disk. Similarly, the [Co/Fe] vs. [Fe/H] trend shows a hint of an enhancement in the local thick disk. The trends of V and Co in the bulge appear to be even more enhanced, although within the uncertainties. The decreasing value of [Sc/Fe] with increasing metallicity is observed in all the components, while our [Mn/Fe] value steadily increases with increasing metallicity in the local disk and the bulge instead. For Cr and Ni we find a flat trend following iron for the whole metallicity range in the disk and the bulge. The ratio of [Ni/Fe] appears slightly overabundant in the thick disk and the bulge compared to the thin disk, although the difference is minor. Conclusions. The somewhat enhanced ratios of [V/Fe] and [Co/Fe] observed in the bulge suggest that the local thick disk and the bulge might have experienced different chemical enrichment and evolutionary paths. However, we are unable to predict the exact evolutionary path of the bulge solely based on these observations. Galactic chemical evolution models could, on the other hand, allow us to predict them using these results.

  • 34.
    Lundberg, H.
    et al.
    Department of Physics, Lund Institute of Technology, PO Box 118, 22100 Lund, Sweden.
    Johansson, S.
    Department of Physics, Lund University, PO Box 118, 22100 Lund, Sweden.
    Nilsson, H.
    Department of Physics, Lund University, PO Box 118, 22100 Lund, Sweden.
    Zhang, Z.
    Department of Physics, Lund Institute of Technology, PO Box 118, 22100 Lund, Sweden.
    New laboratory lifetime measurements of U II for the uranium cosmochronometer2001In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 372, no 3, p. L50-L52Article in journal (Refereed)
    Abstract [en]

    We present new measurements of radiative lifetimes for six energy levels of singly ionized uranium, U II, using laser-induced fluorescence technique. One of the levels, 5f36d7p6M13/2 at 26191 cm-1, decays by a transition at 3859.6 Å. This line has recently been observed in the spectrum of the metal-poor star CS1082-001, the first detection of uranium outside the solar system. The λ3859 line can be used as the presently most accurate cosmochronometer (Cayrel et al. 2001). Our value of the lifetime of the 6M13/2 level is 18.6 ± 0.7 ns, and it confirms the f-value used in the Nature article by Cayrel et al. (2001), which is based on an experimental lifetime of 20 ± 5 ns (Chen & Borzileri 1981). The new measurement also removes the doubt about the choice between that value and other f-values in the literature, differing by a factor of 3. Adopting the same branching fraction as Chen & Borzileri (1981) for the 3859.6 Å line, we derive a gf-value of 0.68, which is 8% higher than the value used by Cayrel et al. (2001). Of significance for the chronometer is also the reduced uncertainty of the radiative lifetime, 4% compared to 25%, and consequently of the f-value, which should decrease the uncertainty in the determination of the stellar age considerably.

  • 35.
    Lundqvist, M.
    et al.
    Atomic Astrophysics, Lund Observatory, Lund University, Box 43, 221 00 Lund.
    Nilsson, H.
    Atomic Astrophysics, Lund Observatory, Lund University, Box 43, 221 00 Lund.
    Wahlgren, G. M.
    Atomic Astrophysics, Lund Observatory, Lund University, Box 43, 221 00 Lund.
    Lundberg, H.
    Atomic Physics, Department of Physics, Lund Institute of Technology, Box 118, 221 00 Lund, Sweden.
    Xu, H. L.
    Atomic Physics, Department of Physics, Lund Institute of Technology, Box 118, 221 00 Lund, Sweden; Department of Physics, Jilin University, ChangChun, 130023, PR China; Department of Physics, Engineering and Optics, Laval University, Quebec City, G1K 7P4, Canada.
    Jang, Z.-K.
    Department of Physics, Jilin University, ChangChun, 130023, PR China.
    Leckrone, D. S.
    Laboratory for Astronomy and Solar Physics, NASA Goddard Space Flight Center, Code 681, Greenbelt, MD, 20771, USA.
    Improved oscillator strengths and wavelengths in Hf II, with applications to stellar elemental abundances2006In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 450, no 1, p. 407-413Article in journal (Refereed)
    Abstract [en]

    Aims. We present new and improved radiative lifetimes for eight levels in Hf I and 18 levels in Hf II, along with oscillator strengths and wavelengths for 195 transitions in Hf II. With these data we determine the abundance of hafnium in two chemically peculiar stars: the hot-Am star HR 3383 and the HgMn star chi; Lupi, and discuss the implications of the new data to the hafnium abundance for the Sun and the metal-poor galactic halo stars CS 22892-052 and CS 31082-001. Methods. The oscillator strengths are derived by combining radiative lifetimes measured with the laser induced fluorescence technique and branching fractions determined from intensity calibrated Fourier transform spectra. The hafnium abundance in the two sharp-lined peculair stars is determined by comparison of spectra obtained from instruments onboard the Hubble Space Telescope with synthetic spectra, while the abundance of hafnium in the solar photosphere and the metal-poor halo stars is discussed in terms of rescaling previous investigations using the new gf values. Results. The abundance enhancement of hafnium has been determined in HR 3383 to be +1.7 dex and that for χ Lupi A is +1.3 dex. In the course of the analysis we have also determined an abundance enhancement for molybdenum in HR 3383 to be +1.2 dex, which is similar to that known for χ Lupi A. The abundances in the metal-poor halo stars CS 31082-001 and CS 22892-052 were rescaled to log e(Hf) = -0.75 and -0.82 respectively, with smaller 1σ uncertainty. This has the effect of improving the theoretical fits of r-process nucleosynthesis to abundance data for heavy elements. The change of gf values also implies that the hafnium abundance in the solar photosphere should be reduced by up to 0.2 dex, thereby inducing a discrepancy with the meteoritic hafnium abundance.

  • 36.
    Masseron, T.
    et al.
    Inst Astrofis Canarias, Tenerife 38205, Spain.;Univ La Laguna, Dept Astrofis, E-38206 Tenerife, Spain..
    Garcia-Hernandez, D. A.
    Inst Astrofis Canarias, Tenerife 38205, Spain.;Univ La Laguna, Dept Astrofis, E-38206 Tenerife, Spain..
    Meszaros, Sz.
    Eotvos Lorand Univ, Gothard Astrophys Observ, Szombathely, Hungary.;Hungarian Acad Sci, Budapest, Hungary..
    Zamora, O.
    Inst Astrofis Canarias, Tenerife 38205, Spain.;Univ La Laguna, Dept Astrofis, E-38206 Tenerife, Spain..
    Dell'Agli, F.
    Inst Astrofis Canarias, Tenerife 38205, Spain.;Univ La Laguna, Dept Astrofis, E-38206 Tenerife, Spain..
    Allende Prieto, C.
    Inst Astrofis Canarias, Tenerife 38205, Spain.;Univ La Laguna, Dept Astrofis, E-38206 Tenerife, Spain..
    Edvardsson, B.
    Uppsala Univ, Theoret Astrophys, Dept Phys & Astron, Box 516, S-75120 Uppsala, Sweden..
    Shetrone, M.
    Univ Texas Austin, McDonald Observ, Ft Davis, TX 79734 USA..
    Plez, B.
    Univ Montpellier, CNRS, Lab Univers & Particules Montpellier, F-34095 Montpellier 05, France..
    Fernandez-Trincado, J. G.
    Univ Atacama, Inst Astron & Ciencias Planetarias, Copayapu 485, Copiapo, Chile.;Univ Concepcion, Dept Astron, Casilla 160-C, Concepcion, Chile.;Univ Bourgogne Franche Comte, Inst Utinam, CNRS, UMR 6213,THETA Franche Comte,Observ Besancon, BP 1615, F-25010 Besancon, France..
    Cunha, K.
    Observ Nacl MCTI, Rua Gen Jose Cristino 77, BR-20921400 Rio De Janeiro, Brazil.;Univ Arizona, Steward Observ, Tucson, AZ 85719 USA..
    Jönsson, H.
    Lund Univ, Lund Observ, Dept Astron & Theoret Phys, Box 43, S-22100 Lund, Sweden..
    Geisler, D.
    Univ Concepcion, Dept Astron, Casilla 160-C, Concepcion, Chile.;Univ La Serena, Inst Invest Multidisciplinario Ciencia & Tecnol, Ave Raul Bitran S-N, La Serena, Chile.;Univ La Serena, Dept Fis & Astron, Fac Ciencias, Ave Juan Cisternas, La Serena 1200, Chile..
    Beers, T. C.
    Univ Notre Dame, Dept Phys, Notre Dame, IN 46556 USA.;Univ Notre Dame, JINA Ctr Evolut Elements, Notre Dame, IN 46556 USA..
    Cohen, R. E.
    Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21210 USA..
    Homogeneous analysis of globular clusters from the APOGEE survey with the BACCHUS code2019In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 622, article id A191Article in journal (Refereed)
    Abstract [en]

    Aims. We seek to provide abundances of a large set of light and neutron-capture elements homogeneously analyzed that cover a wide range of metallicity to constrain globular cluster (GC) formation and evolution models. Methods. We analyzed a large sample of 885 GCs giants from the SDSS IV-Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey. We used the Cannon results to separate the red giant branch and asymptotic giant branch stars, not only allowing for a refinement of surface gravity from isochrones, but also providing an independent H-band spectroscopic method to distinguish stellar evolutionary status in clusters. We then used the Brussels Automatic Code for Characterizing High accUracy Spectra (BACCHUS) to derive metallicity, microturbulence, macroturbulence, many light-element abundances, and the neutron-capture elements Nd and Ce for the first time from the APOGEE GCs data. Results. Our independent analysis helped us to diagnose issues regarding the standard analysis of the APOGEE DR14 for low-metallicity GC stars. Furthermore, while we confirm most of the known correlations and anticorrelation trends (Na-O, Mg-Al, C-N), we discover that some stars within our most metal-poor clusters show an extreme Mg depletion and some Si enhancement. At the same time, these stars show some relative Al depletion, displaying a turnover in the Mg-Al diagram. These stars suggest that Al has been partially depleted in their progenitors by very hot proton-capture nucleosynthetic processes. Furthermore, we attempted to quantitatively correlate the spread of Al abundances with the global properties of GCs. We find an anticorrelation of the Al spread against clusters metallicity and luminosity, but the data do not allow us to find clear evidence of a dependence of N against metallicity in the more metal-poor clusters. Conclusions. Large and homogeneously analyzed samples from ongoing spectroscopic surveys unveil unseen chemical details for many clusters, including a turnover in the Mg-Al anticorrelation, thus yielding new constrains for GCs formation/evolution models.

  • 37.
    Montelius, M.
    et al.
    Univ Groningen, Kapteyn Astron Inst, Landleven 12, NL-9747 AD Groningen, Netherlands.;Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden..
    Forsberg, R.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden..
    Ryde, N.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden..
    Jönsson, H.
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM). Malmo Univ, Mat Sci & Appl Math, S-20506 Malmo, Sweden..
    Afsar, M.
    Ege Univ, Dept Astron & Space Sci, TR-35100 Izmir, Turkey.;Univ Texas Austin, Dept Astron, Austin, TX 78712 USA.;Univ Texas Austin, McDonald Observ, Austin, TX 78712 USA..
    Johansen, A.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden.;Univ Copenhagen, GLOBE Inst, Ctr Star & Planet Format, Oster Voldgade 5-7, DK-1350 Copenhagen, Denmark..
    Kaplan, K. F.
    NASA, SOFIA Sci Ctr USRA, Ames Res Ctr, Moffett Field, CA 94035 USA..
    Kim, H.
    Gemini Observ NOIRLab, Casilla 603, La Serena, Chile..
    Mace, G.
    Univ Texas Austin, Dept Astron, Austin, TX 78712 USA.;Univ Texas Austin, McDonald Observ, Austin, TX 78712 USA..
    Sneden, C.
    Univ Texas Austin, Dept Astron, Austin, TX 78712 USA.;Univ Texas Austin, McDonald Observ, Austin, TX 78712 USA..
    Thorsbro, B.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden..
    Chemical evolution of ytterbium in the Galactic disk2022In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 665, article id A135Article in journal (Refereed)
    Abstract [en]

    Context. Measuring the abundances of neutron-capture elements in Galactic disk stars is an important part of understanding key stellar and galactic processes. In the optical wavelength regime a number of different neutron-capture elements have been measured; however, only the s-process-dominated element cerium has been accurately measured for a large sample of disk stars from the infrared H band. The more r-process dominated element ytterbium has only been measured in a small subset of stars so far. Aims. In this study we aim to measure the ytterbium (Yb) abundance of local disk giants using the Yb II line at lambda(air) = 16 498 angstrom. We also compare the resulting abundance trend with cerium and europium abundances for the same stars to analyse the s- and r-process contributions. Methods. We analyse 30 K giants with high-resolution H band spectra using spectral synthesis. The very same stars have already been analysed using high-resolution optical spectra via the same method, but it was not possible to determine the abundance of Yb from those spectra due to blending issues for stars with [Fe/H] > -1. In the present analysis, we utilise the stellar parameters determined from the optical analysis. Results. We determined the Yb abundances with an estimated uncertainty for [Yb/Fe] of 0.1 dex. By comparison, we found that the [Yb/Fe] trend closely follows the [Eu/Fe] trend and has clear s-process enrichment in identified s-rich stars. This comparison confirms both that the validity of the Yb abundances is ensured and that the theoretical prediction that the s-/r-process contribution to the origin of Yb of roughly 40/60 is supported. Conclusions. These results show that, with a careful and detailed analysis of infrared spectra, reliable Yb abundances can be derived for a wider sample of cooler giants in the range -1.1 < [Fe/H] < 0.3. This is promising for further studies of the production of Yb and for the r-process channel, key for galactochemical evolution, in the infrared.

  • 38.
    Nandakumar, G.
    et al.
    Lund Univ, Dept Phys, Div Astrophys, Box 43, S-22100 Lund, Sweden..
    Ryde, N.
    Lund Univ, Dept Phys, Div Astrophys, Box 43, S-22100 Lund, Sweden..
    Forsberg, R.
    Lund Univ, Dept Phys, Div Astrophys, Box 43, S-22100 Lund, Sweden..
    Montelius, M.
    Univ Groningen, Kapteyn Astron Inst, Landleven 12, NL-9747 AD Groningen, Netherlands..
    Mace, G.
    Univ Texas Austin, Dept Astron, Austin, TX 78712 USA.;Univ Texas Austin, McDonald Observ, Austin, TX 78712 USA..
    Jönsson, Henrik
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Thorsbro, B.
    Lund Univ, Dept Phys, Div Astrophys, Box 43, S-22100 Lund, Sweden.;CNRS, UMR 7293, Observ Cote Dazur, Lab Lagrange,BP4229, F-06304 Nice 4, France..
    M giants with IGRINS III. Abundance trends for 21 elements in the solar neighborhood from high-resolution near-infrared spectra2024In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 684, article id A15Article in journal (Refereed)
    Abstract [en]

    Context. To be able to investigate the chemical history of the entire Milky Way, it is imperative to also study its dust-obscured regions in detail, as this is where most of the mass lies. The Galactic Center is an example of such a region. Due to the intervening dust along the line of sight, near-infrared spectroscopic investigations are necessary to study this region of interest. Aims. The aim of this work is to demonstrate that M giants observed at high spectral resolution in the H- and K-bands (1.5-2.4 mu m) can yield useful abundance ratio trends versus metallicity for 21 elements. These elements can then also be studied for heavily dust-obscured regions of the Galaxy, such as the Galactic Center. The abundance ratio trends will be important for further investigation of the Galactic chemical evolution in these regions. Methods. We observed near-infrared spectra of 50 M giants in the solar neighborhood at high signal-to-noise and at a high spectral resolution with the IGRINS spectrometer on the Gemini South telescope. The full H- and K-bands were recorded simultaneously at R = 45 000. Using a manual spectral synthesis method, we determined the fundamental stellar parameters for these stars and derived the stellar abundances for 21 atomic elements, namely, F, Mg, Si, S, Ca, Na, Al, K, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Y, Ce, Nd, and Yb. We systematically studied useful spectral lines of all these elements in the H- and K-bands. Results. We demonstrate that elements can be analyzed from H- and K-band high-resolution spectra, and we show which spectral lines can be used for an abundance analysis, identifying them line by line. We discuss the 21 abundance ratio trends and compare them with those determined from APOGEE and from the optical Giants in the Local Disk (GILD) sample. From high-resolution H- and K-band spectra, the trends of the heavy elements Cu, Zn, Y, Ce, Nd, and Yb can be retrieved. This opens up the nucleosynthetic channels, including the s-process and the r-process in dust-obscured populations. The [Mn/Fe] versus [Fe/H] trend is shown to be more or less flat at low metallicities, implying that existing non-local thermodynamic equilibrium correction is relevant. Conclusions. With high-resolution near-infrared spectra, it is possible to determine reliable abundance ratio trends versus metallicity for 21 elements, including elements formed in several different nucleosynthetic channels. It is also possible to determine the important neutron-capture elements, both s- and r-dominated elements. This opens up the possibility to study the chemical evolution in detail of dust-obscured regions of the Milky Way, such as the Galactic Center. The M giants are useful bright probes for these regions and for future studies of extra-galactic stellar populations. A careful analysis of high-quality spectra is needed to retrieve all of these elements, which are often from weak and blended lines. A spectral resolution of R greater than or similar to 40 000 is a further quality that helps in deriving precise abundances for this range of elements. In comparison to APOGEE, we can readily obtain the abundances for Cu, Ce, Nd, and Yb from the H-band, demonstrating an advantage of analyzing high-resolution spectra.

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  • 39.
    Nandakumar, G.
    et al.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden..
    Ryde, N.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden..
    Montelius, M.
    Univ Groningen, Kapteyn Astron Inst, Landleven 12, NL-9747 AD Groningen, Netherlands..
    Thorsbro, B.
    Univ Tokyo, Sch Sci, Dept Astron, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1130033, Japan..
    Jönsson, Henrik
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM). Malmo Univ, Mat Sci & Appl Math, S-20506 Malmo, Sweden..
    Mace, G.
    Univ Texas Austin, Dept Astron, RLM 15308, Austin, TX 78712 USA.;Univ Texas Austin, McDonald Observ, Austin, TX 78712 USA..
    The Galactic chemical evolution of phosphorus observed with IGRINS2022In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 668, article id A88Article in journal (Refereed)
    Abstract [en]

    Context. Phosphorus (P) is considered to be one of the key elements for life, making it an important element to look for in the abundance analysis of spectra of stellar systems. Yet, only a select number of spectroscopic studies exist to estimate the phosphorus abundances and investigate its trend across a range of metallicities. This is due to the lack of good phosphorus lines in the optical wavelength region and the requirement of careful manual analysis of the blended phosphorus lines in near-infrared H-band spectra obtained with individual observations and surveys such as the Apache Point Observatory Galactic Evolution Experiment (APOGEE). Aims. Based on a consistent and systematic analysis of high-resolution, near-infrared Immersion GRating INfrared Spectrograph (IGRINS) spectra of 38 K giant stars in the Solar neighborhood, we present and investigate the phosphorus abundance trend in the metallicity range of -1.2 dex < [Fe/H] < 0.4 dex. Furthermore, we compare this trend with the available chemical evolution models to shed some light on the origin and evolution of phosphorus. Methods. We have observed full H- and K-band spectra at a spectral resolving power of R = 45 000 with IGRINS mounted on the Gemini South telescope, the Discovery Channel Telescope, and the Harlan J Smith Telescope at McDonald Observatory. Abundances were determined from spectral lines by modeling the synthetic spectrum that best matches the observed spectrum by chi(2) minimization. For this task, we used the Spectroscopy Made Easy (SME) tool in combination with one-dimensional (1D) Model Atmospheres in a Radiative and Convective Scheme (MARCS) stellar atmosphere models. The investigated sample of stars have reliable stellar parameters estimated using optical FIber-fed Echelle Spectrograph (FIES) spectra obtained in a previous study of a set of stars called Giants in the Local Disk (GILD). In order to determine the phosphorus abundances from the 16482.92 angstrom phosphorus line, we needed to take special care blending the CO(v = 7-4) line. With the stellar parameters known, we thus determined the C, N, and O abundances from atomic carbon and a range of nonblended molecular lines (CO, CN, and OH) which are plentiful in the H-band region of K giant stars, assuring an appropriate modeling of the blending CO(v = 7-4) line. Results. We present the [P/Fe] versus [Fe/H] trend for K giant stars in the metallicity range of -1.2 dex < [Fe/H] < 0.4 dex and enhanced phosphorus abundances for two metal-poor s-rich stars. We find that our trend matches well with the compiled literature sample of prominently dwarf stars and the limited number of giant stars. Our trend is found to be higher by similar to 0.05-0.1 dex compared to the theoretical chemical evolution trend resulting from the core collapse supernova (type II) of massive stars with the phosphorus yields arbitrarily increased by a factor of 2.75. Thus the enhancement factor might need to be similar to 0.05-0.1 dex higher to match our trend. We also find an empirically determined primary behavior for phosphorus. Furthermore, the phosphorus abundance is found to be elevated by similar to 0.6-0.9 dex in the two s-enriched stars compared to the theoretical chemical evolution trend.

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  • 40. Nicholls, Christine P
    et al.
    Lebzelter, T
    Smette, A
    Wolff, B
    Hartman, Henrik
    Malmö högskola, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Käufl, H.-U.
    Przybilla, N.
    Ramsay, S.
    Uttenthaler, S.
    Wahlgren, G.
    Bagnulo, G
    Hussain, G
    Nieva, M.-F.
    Seemann, U
    Seifahrt, A.
    CRIRES-POP: a library of high resolution spectra in the near-infrared II. Data reduction and the spectrum of the K giant 10 Leonis2017In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 598, article id A79Article in journal (Refereed)
    Abstract [en]

    Context. High resolution stellar spectral atlases are valuable resources to astronomy. They are rare in the 1 − 5 μm region for historical reasons, but once available, high resolution atlases in this part of the spectrum will aid the study of a wide range of astrophysical phenomena. Aims. The aim of the CRIRES-POP project is to produce a high resolution near-infrared spectral library of stars across the H-R diagram. The aim of this paper is to present the fully reduced spectrum of the K giant 10 Leo that will form the basis of the first atlas within the CRIRES-POP library, to provide a full description of the data reduction processes involved, and to provide an update on the CRIRES-POP project. Methods. All CRIRES-POP targets were observed with almost 200 different observational settings of CRIRES on the ESO Very Large Telescope, resulting in a basically complete coverage of its spectral range as accessible from the ground. We reduced the spectra of 10 Leo with the CRIRES pipeline, corrected the wavelength solution and removed telluric absorption with Molecfit, then resampled the spectra to a common wavelength scale, shifted them to rest wavelengths, flux normalised, and median combined them into one final data product. Results. We present the fully reduced, high resolution, near-infrared spectrum of 10 Leo. This is also the first complete spectrum from the CRIRES instrument. The spectrum is available online. Conclusions. The first CRIRES-POP spectrum has exceeded our quality expectations and will form the centre of a state-of-the-art stellar atlas. This first CRIRES-POP atlas will soon be available, and further atlases will follow. All CRIRES-POP data products will be freely and publicly available online.

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  • 41.
    Nilsson, H.
    et al.
    Lund Observatory, Lund University, Box 43, 22100 Lund, Sweden.
    Andersson, J.
    Department of Physics, University of Gothenburg, 412 96 Gothenburg, Sweden.
    Engström, L.
    Department of Physics, Lund University, Box 118, 22100 Lund, Sweden.
    Lundberg, H.
    Department of Physics, Lund University, Box 118, 22100 Lund, Sweden.
    Hartman, H.
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM). Lund Observatory, Lund University, Box 43, 22100 Lund, Sweden.
    Experimental transition probabilities for 4p-4d spectral lines in V II2019In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 622, article id A154Article in journal (Refereed)
    Abstract [en]

    Aims. We aim to measure lifetimes of levels belonging to the 3d(3)(F-4)4d subconfiguration in V II, and derive absolute transition probabilities by combining the lifetimes with experimental branching fractions. Methods. The lifetimes were measured using time-resolved laser-induced fluorescence in a two-photon excitation scheme. The branching fractions were measured in intensity calibrated spectra from a hollow cathode discharge lamp, recorded with a Fourier transform spectrometer. Results. We report lifetimes for 13 levels at an energy around 73 000 cm(-1). Absolute transition probabilities of 78 lines are derived by combining the lifetimes and branching fractions. The experimental values are compared with theoretical data from the literature.

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  • 42.
    Nilsson, H.
    et al.
    Lund Observatory, Lund University, Box 43, 22100 Lund, Sweden.
    Engström, L.
    Department of Physics, Lund University, Box 118, 22100 Lund, Sweden.
    Lundberg, H.
    Department of Physics, Lund University, Box 118, 22100 Lund, Sweden.
    Hartman, H.
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM). Lund Observatory, Lund University, Box 43, 22100 Lund, Sweden.
    Palmeri, P.
    Physique Atomique et Astrophysique, Université de Mons, 7000 Mons, Belgium.
    Quinet, P.
    Physique Atomique et Astrophysique, Université de Mons, 7000 Mons, Belgium; IPNAS, Université de Liège, 4000 Liège, Belgium.
    Experimental and theoretical lifetimes and transition probabilities for spectral lines in Nb II2019In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 627, article id A102Article in journal (Refereed)
    Abstract [en]

    Aims. We have measured and calculated lifetimes of high lying levels in Nb II, and derived absolute transition probabilities by combining the lifetimes with experimental branching fractions. Methods. The lifetimes were measured using time-resolved laser-induced fluorescence in a two-photon and two-step excitation scheme. The branching fractions were measured in intensity calibrated spectra from a hollow cathode discharge, recorded with a Fourier transform spectrometer. The calculations were performed with the relativistic Hartree-Fock method including core polarization. Results. We report experimental lifetimes of 13 levels in the 4d(3)(F-4)5d and 4d(3)(F-4)6s subconfigurations, at an energy around 70 000 cm(-1). By combining the lifetimes with experimental branching fractions absolute transition probabilities of 59 lines are derived. The experimental results are compared with calculated values.

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  • 43.
    Nilsson, H.
    et al.
    Lund Observatory, Lund University, Box 43, 221 00 Lund, Sweden.
    Hartman, H.
    Lund Observatory, Lund University, Box 43, 221 00 Lund, Sweden.
    Engström, L.
    Department of Physics, Lund University, Box 118, 221 00 Lund, Sweden.
    Lundberg, H.
    Department of Physics, Lund University, Box 118, 221 00 Lund, Sweden.
    Sneden, C.
    Department of Astronomy, University of Texas, RLM 15.308, Austin TX78712, USA.
    Fivet, V.
    Astrophysique et Spectroscopie, Université de Mons, 20 Place du Parc, 7000 Mons, Belgium.
    Palmeri, P.
    Astrophysique et Spectroscopie, Université de Mons, 20 Place du Parc, 7000 Mons, Belgium.
    Quinet, P.
    Astrophysique et Spectroscopie, Université de Mons, 20 Place du Parc, 7000 Mons, Belgium; IPNAS, Bât. B15, Université de Liège, Sart Tilman, 4000 Liège, Belgium.
    Biémont, É.
    Astrophysique et Spectroscopie, Université de Mons, 20 Place du Parc, 7000 Mons, Belgium; IPNAS, Bât. B15, Université de Liège, Sart Tilman, 4000 Liège, Belgium.
    Transition probabilities of astrophysical interest in the niobium ions Nb+ and Nb2+2010In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 511, article id A16Article in journal (Refereed)
    Abstract [en]

    Aims. We attempt to derive accurate transition probabilities for astrophysically interesting spectral lines of Nb II and Nb III and determine the niobium abundance in the Sun and metal-poor stars rich in neutron-capture elements.Methods. We used the time-resolved laser-induced fluorescence technique to measure radiative lifetimes in Nb II. Branching fractions were measured from spectra recorded using Fourier transform spectroscopy. The radiative lifetimes and the branching fractions were combined yielding transition probabilities. In addition, we calculated lifetimes and transition probablities in Nb II and Nb III using a relativistic Hartree-Fock method that includes core polarization. Abundances of the sun and five metal-poor stars were derived using synthetic spectra calculated with the MOOG code, including hyperfine broadening of the lines.Results. We present laboratory measurements of 17 radiative lifetimes in Nb II. By combining these lifetimes with branching fractions for lines depopulating the levels, we derive the transition probabilities of 107 Nb II lines from 4d35p configuration in the wavelength region 2240-4700 Å. For the first time, we present theoretical transition probabilities of 76 Nb III transitions with wavelengths in the range 1430-3140 Å. The derived solar photospheric niobium abundance log    = 1.44   0.06 is in agreement with the meteoritic value. The stellar Nb/Eu abundance ratio determined for five metal-poor stars confirms that the r-process is a dominant production method for the n-capture elements in these stars.

  • 44.
    Nilsson, H.
    et al.
    Atomic Astrophysics, Lund Observatory, Box 43, 221 00 Lund.
    Ivarsson, S.
    Atomic Astrophysics, Lund Observatory, Box 43, 221 00 Lund.
    Experimental oscillator strengths and hyperfine constants in Nb ii2008In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 492, no 2, p. 609-616Article in journal (Refereed)
    Abstract [en]

    We used high-resolution Fourier transform spectroscopy to measure new and improved transition probabilities and hyperfine data for singly ionized niobium. Intensity calibrated spectra were used to measure branching fractions of 145 Nb II lines in the wavelength interval 2600–4600 Å. Combining the branching fractions with previously reported lifetimes, absolute oscillator strengths for these 145 transitions were derived. In addition, line structures due to magnetic hyperfine interaction were studied resulting in new hyperfine splitting constants for 28 even and 24 odd energy levels.


     

  • 45.
    Nilsson, H.
    et al.
    Lund Observatory, Lund University, PO Box 43, 22100 Lund, Sweden.
    Ivarsson, S.
    Lund Observatory, Lund University, PO Box 43, 22100 Lund, Sweden.
    Johansson, S.
    Lund Observatory, Lund University, PO Box 43, 22100 Lund, Sweden.
    Lundberg, H.
    Department of Physics, Lund Institute of Technology, PO Box 118, 22100 Lund.
    Experimental oscillator strengths in U II of cosmological interest2002In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 381, no 3, p. 1090-1093Article in journal (Refereed)
    Abstract [en]

    Oscillator strengths for 57 U II lines in the region 3500–6700 Å  have been derived by combining new branching fraction measurements with recently measured lifetimes. The lines combine six upper levels with numerous low levels having excitation energies of 0–1.5 eV. The data include the U II line at 3859 Å, which is used for cosmochronology.

     

  • 46.
    Nilsson, H.
    et al.
    Atomic Astrophysics, Lund Observatory, Lund University, Box 43, 221 00 Lund, Sweden.
    Ljung, G.
    Atomic Astrophysics, Lund Observatory, Lund University, Box 43, 221 00 Lund, Sweden.
    Lundberg, H.
    Atomic Physics, Department of Physics, Lund Institute of Technology, Box 118, 221 00 Lund, Sweden.
    Nielsen, K. E.
    Catholic University of America, Washington, DC 20064, USA; Exploration of the Universe Division, Code 667, Goddard Space Flight Center, Greenbelt, MD 20771, USA.
    The FERRUM project: improved experimental oscillator strengths in Cr II2006In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 445, no 3, p. 1165-1168Article in journal (Refereed)
    Abstract [en]

    We report absolute oscillator strengths for 119   transitions in the wavelength region 2050-4850 Å. The transition probabilities have been derived by combining radiative lifetimes, measured with time-resolved laser induced fluorescence, and branching fractions from intensity calibrated Fouirer transform spectrometer data. New radiative lifetimes for the 3d4(5D)4p 4F, 4D and 6P terms are reported, adding up to a total of 25 energy levels with measured lifetimes used to derive this improved set of atomic data.


     

  • 47.
    Nilsson, H.
    et al.
    Atomic Astrophysics, Lund Observatory, Lund University, PO Box 43, 22100 Lund, Sweden.
    Zhang, Z. G.
    Atomic Physics, Department of Physics, Lund Institute of Technology, PO Box 118, 22100 Lund, Sweden.
    Lundberg, H.
    Atomic Physics, Department of Physics, Lund Institute of Technology, PO Box 118, 22100 Lund, Sweden.
    Johansson, S.
    Atomic Astrophysics, Lund Observatory, Lund University, PO Box 43, 22100 Lund, Sweden.
    Nordström, B.
    Atomic Astrophysics, Lund Observatory, Lund University, PO Box 43, 22100 Lund, Sweden; Niels Bohr Institute for Astronomy, Physics & Geophysics, Juliane Marie vej 30, 2100 Copenhagen, Denmark.
    Experimental oscillator strengths in Th II2002In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 382, no 1, p. 368-377Article in journal (Refereed)
    Abstract [en]

    We have measured radiative lifetimes of ten Th II levels by using the laser-induced fluorescence technique and branching fractions with Fourier transform spectroscopy. By combining the new branching fractions with a total of 23 lifetimes, from the present work and from measurements by Simonsen et al. ([CITE]), absolute oscillator strengths for 180 lines have been derived. Some of these new f-values reported are relevant for radioactive dating of stars.

     

  • 48.
    Papoulia, Asimina
    et al.
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM). Division of Mathematical Physics, Lund University.
    Ekman, Jörgen
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Jönsson, Per
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Extended transition rates and lifetimes in Al I and Al II from systematic multiconfiguration calculations2018In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 621, article id A16Article in journal (Refereed)
    Abstract [en]

    MultiConfiguration Dirac-Hartree-Fock (MCDHF) and relativistic configuration interaction (RCI) calculations were performed for 28 and 78 states in neutral and singly ionized aluminium, respectively. In Al I, the configurations of interest are 3s(2)nl for n = 3, 4, 5 with l = 0 to 4, as well as 3s3p(2) and 3s(2)6l for l = 0, 1, 2. In Al II, in addition to the ground configuration 3s(2), the studied configurations are 3snl with n = 3 to 6 and l = 0 to 5, 3p(2), 3s7s, 3s7p, and 3p3d. Valence and core-valence electron correlation effects are systematically accounted for through large configuration state function (CSF) expansions. Calculated excitation energies are found to be in excellent agreement with experimental data from the National Institute of Standards and Technology (NIST) database. Lifetimes and transition data for radiative electric dipole (E1) transitions are given and compared with results from previous calculations and available measurements for both Al I and Al II. The computed lifetimes of Al I are in very good agreement with the measured lifetimes in high-precision laser spectroscopy experiments. The present calculations provide a substantial amount of updated atomic data, including transition data in the infrared region. This is particularly important since the new generation of telescopes are designed for this region. There is a significant improvement in accuracy, in particular for the more complex system of neutral Al I. The complete tables of transition data are available at the CDS.

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  • 49.
    Pehlivan, Asli
    et al.
    Malmö högskola, Faculty of Technology and Society (TS). Lund Observatory, Box 43, 221 00 Lund, Sweden.
    Nilsson, Hampus
    Lund Observatory, Box 43, 221 00 Lund, Sweden.
    Hartman, Henrik
    Malmö högskola, Faculty of Technology and Society (TS). Lund Observatory, Box 43, 221 00 Lund, Sweden.
    Laboratory oscillator strengths of Sc i in the near-infrared region for astrophysical applications2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 582, no A98, article id A98Article in journal (Refereed)
    Abstract [en]

    Context. Atomic data is crucial for astrophysical investigations. To understand the formation and evolution of stars, we need to analyse their observed spectra. Analysing a spectrum of a star requires information about the properties of atomic lines, such as wavelengths and oscillator strengths. However, atomic data of some elements are scarce, particularly in the infrared region, and this paper is part of an effort to improve the situation on near-IR atomic data. Aims. This paper investigates the spectrum of neutral scandium, Sc i, from laboratory measurements and improves the atomic data of Sc i lines in the infrared region covering lines in R, I, J, and K bands. Especially, we focus on measuring oscillator strengths for Sc i lines connecting the levels with 4p and 4s configurations. Methods. We combined experimental branching fractions with radiative lifetimes from the literature to derive oscillator strengths (f -values). Intensity-calibrated spectra with high spectral resolution were recorded with Fourier transform spectrometer from a hollow cathode discharge lamp. The spectra were used to derive accurate oscillator strengths and wavelengths for Sc i lines, with emphasis on the infrared region. Results. This project provides the first set of experimental Sc i lines in the near-infrared region for accurate spectral analysis of astronomical objects. We derived 63 log(g f ) values for the lines between 5300 Å and 24 300 Å. The uncertainties in the f -values vary from 5% to 20%. The small uncertainties in our values allow for an increased accuracy in astrophysical abundance determinations

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  • 50.
    Pehlivan Rhodin, Asli
    et al.
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM). Lund Univ, Dept Phys, Div Astrophys, SE-221 00 Lund, Sweden..
    Hartman, Henrik
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Nilsson, Hampus
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Jönsson, Per
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Accurate and experimentally validated transition data for Si I and Si II2024In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 682, article id A184Article in journal (Refereed)
    Abstract [en]

    Aims. The aim of this study is to provide radiative data for neutral and singly ionised silicon, in particular for the first experimental oscillator strengths for near-infrared Si I lines. In addition, we aim to perform atomic structure calculations both for neutral and singly ionised silicon while including lines from highly excited levels.

    Methods. We performed large-scale atomic structure calculations with the relativistic multiconfiguration Dirac-Hartree-Fock method using the GRASP2K package to determine log(𝑔ƒ) values of Si I and Si II lines, taking into account valence-valence and core-valence electron correlation. In addition, we derived oscillator strengths of near-infrared Si I lines by combining the experimental branching fractions with radiative lifetimes from our calculations. The silicon plasma was obtained from a hollow cathode discharge lamp, and the intensity-calibrated high-resolution spectra between 1037 and 2655 nm were recorded by a Fourier transform spectrometer.

    Results. We provide an extensive set of accurate experimental and theoretical log(𝑔ƒ) values. For the first time, we derived 17 log(𝑔ƒ) values of Si I lines in the infrared from experimental measurements. We report data for 1500 Si I lines and 500 Si II lines. The experimental uncertainties of our ƒ-values vary between 5% for the strong lines and 25% for the weak lines. The theoretical log(𝑔ƒ) values for Si I lines in the range 161 nm to 6340 nm agree very well with the experimental values of this study and complete the missing transitions involving levels up to 3s23p7s (61 970 cm−1). In addition, we provide accurate calculated log(𝑔ƒ) values of Si II lines from the levels up to 3s27f (122 483 cm−1) in the range 81 nm to 7324 nm.

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