Publikationer från Malmö universitet
Ändra sökning
Avgränsa sökresultatet
12 1 - 50 av 67
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Pehlivan Rhodin, Asli
    et al.
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM). Lund Univ, Dept Phys, Div Astrophys, SE-221 00 Lund, Sweden..
    Hartman, Henrik
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Nilsson, Hampus
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Jönsson, Per
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Accurate and experimentally validated transition data for Si I and Si II2024Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 682, artikel-id A184Artikel i tidskrift (Refereegranskat)
    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.

    Ladda ner fulltext (pdf)
    fulltext
  • 2.
    Gull, Theodore R.
    et al.
    Exoplanets & Stellar Astrophysics Laboratory, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA; Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA.
    Hartman, Henrik
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Teodoro, Mairan
    Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA.
    Hillier, D. John
    Department of Physics & Astronomy & Pittsburgh Particle Physics, Astrophysics, & Cosmology Center (PITT PACC), University of Pittsburgh, 3941 O'Hara Street, Pittsburgh, PA 15260, USA.
    Corcoran, Michael F.
    CRESST & X-ray Astrophysics Laboratory, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA ; The Catholic University of America, 620 Michigan Avenue, N.E. Washington, DC 20064, USA.
    Damineli, Augusto
    Universidade de São Paulo, IAG, Cidade Universitária São Paulo-SP, Rua do Matão 1226, Butantã, São Paulo 05508-090, Brasil.
    Hamaguchi, Kenji
    CRESST & X-ray Astrophysics Laboratory, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA; Department of Physics, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
    Madura, Thomas
    Department of Physics & Astronomy, San Jose State University, One Washington Square, San Jose, CA 95192, USA.
    Moffat, Anthony F. J.
    Dépt. de physique, Univ. de Montréal, C.P. 6128, Succ. C-V, Montréal, QC H3C 3J7, Canada.
    Morris, Patrick
    California Institute of Technology, IPAC, M/C 100-22, Pasadena, CA 91125, USA.
    Nielsen, Krister
    The Catholic University of America, 620 Michigan Avenue, N.E. Washington, DC 20064, USA.
    Richardson, Noel D.
    Department of Physics & Astronomy, Embry-Riddle Aeronautical University, 3700 Willow Creek Road, Prescott, AZ 86301, USA.
    Stevens, Ian R.
    School of Physics & Astronomy, University of Birmingham, Birmingham B15 2TT, UK.
    Weigelt, Gerd
    Max Planck Institute for Radio Astronomy, Auf dem Hügel 69, D-53121 Bonn, Germany.
    Eta Carinae - The Dissipating Occulter Is an Extended Structure2023Ingår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 954, nr 1, artikel-id 104Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Previous Hubble Space Telescope (HST)/Space Telescope Imaging Spectrograph (STIS) longslit observations of Eta Carinae (η Car) identified numerous absorption features in both the stellar spectrum, and in the adjacent nebular spectra, along our line of sight (LOS). The absorption features became temporarily stronger when the ionizing far-ultraviolet radiation field was reduced by the periastron passage of the secondary star. Subsequently, dissipation of a dusty structure in our LOS has led to a long-term increase in the apparent brightness of η Car, an increase in the ionizing ultraviolet (UV) radiation, and the disappearance of absorption from multiple velocity-separated shells extending across the foreground Homunculus lobe. We use HST/STIS spectro-images, coupled with published infrared and radio observations, to locate this intervening dusty structure. The velocity and spatial information indicate the occulter is ≈1000 au in front of η Car. The Homunculus is a transient structure composed of dusty, partially ionized ejecta that eventually will disappear due to the relentless rain of ionizing radiation and wind from the current binary system along with dissipation and mixing with the interstellar medium. This evolving complex continues to provide an astrophysical laboratory that changes on human timescales.

    Ladda ner fulltext (pdf)
    fulltext
  • 3.
    Burheim, Madeleine
    et al.
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM). Lund Observatory, Division of Astrophysics, Department of Physics, Sölvegatan 27, Box 43, 221 00 Lund, Sweden.
    Hartman, Henrik
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Nilsson, Hampus
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Experimental oscillator strengths of Al I lines for near-infrared astrophysical spectroscopy2023Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 672, artikel-id A197Artikel i tidskrift (Refereegranskat)
    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.

     

    Ladda ner fulltext (pdf)
    fulltext
  • 4.
    Damineli, Augusto
    et al.
    Universidade de São Paulo, Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Rua do Matão 1226, Cidade Universitária, São Paulo, Brasil.
    Hillier, Desmond J.
    Department of Physics and Astronomy & Pittsburgh Particle Physics, Astrophysics, and Cosmology Center (PITT PACC), University of Pittsburgh, 3941 O'Hara Street, Pittsburgh, PA 15260, USA.
    Navarete, Felipe
    SOAR Telescope/NSF's NOIRLab, Avenida Juan Cisternas 1500, 1700000, La Serena, Chile.
    Moffat, Anthony F. J.
    Département de Physique and Centre de Recherche en Astrophysique du Québec (CRAQ) Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, Québec, H3C 3J7, Canada.
    Weigelt, Gerd
    Max Planck Institute for Radio Astronomy, Auf dem Hügel 69, D-53121 Bonn, Ge.
    Corcoran, Michael F.
    CRESST II and X-ray Astrophysics Laboratory, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA; The Catholic University of America, 620 Michigan Avenue N.E., Washington, DC 20064, USA.
    Gull, Theodore. R.
    Exoplanets & Stellar Astrophysics Laboratory, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA.
    Richardson, Noel D.
    Department of Physics and Astronomy, Embry-Riddle Aeronautical University, 3700 Willow Creek Road, Prescott, AZ 86301, USA.
    Ho, Peter
    Department of Applied Mathematics, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA.
    Madura, Thomas I.
    Department of Physics and Astronomy, San José State University, One Washington Square, San José, CA 95192-0106, USA.
    Espinoza-Galeas, David
    Departamento de Astronomia y Astrofisica, Facultad de Ciencias Espaciales, Universidad Nacional Autonoma de Honduras, Bulevar Suyapa, Tegucigalpa, M.D.C, Honduras.
    Hartman, Henrik
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Morris, Patrick
    California Institute of Technology, IPAC, M/C 100-22, Pasadena, CA 91125, USA.
    Pickett, Connor S.
    Department of Physics and Astronomy, Embry-Riddle Aeronautical University, 3700 Willow Creek Road, Prescott, AZ 86301, USA.
    Stevens, Ian R.
    School of Physics & Astronomy, University of Birmingham, Birmingham B15 2TT, UK.
    Russell, Christopher M. P.
    Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA.
    Hamaguchi, Kenji
    CRESST II and X-ray Astrophysics Laboratory, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA; Department of Physics, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
    Jablonski, Francisco J.
    Instituto Nacional de Pesquisas Espaciais/MCTIC, Avenida dos Astronautas 1758, São José dos Campos, SP, 12227-010, Brazil.
    Teodoro, Mairan
    Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA.
    McGee, Padric
    Department of Physics, School of Physical Sciences, University of Adelaide, South Australia, 5005, Australia; SASER Team, 269 Domain Road, South Yarra, Vic 3141, Australia.
    Cacella, Paulo
    SASER Team, 269 Domain Road, South Yarra, Vic 3141, Australia.
    Heathcote, Bernard
    SASER Team, 269 Domain Road, South Yarra, Vic 3141, Australia.
    Harrison, Ken M.
    SASER Team, 269 Domain Road, South Yarra, Vic 3141, Australia.
    Johnston, Mark
    SASER Team, 269 Domain Road, South Yarra, Vic 3141, Australia.
    Bohlsen, Terry
    SASER Team, 269 Domain Road, South Yarra, Vic 3141, Australia.
    Di Scala, Giorgio
    SASER Team, 269 Domain Road, South Yarra, Vic 3141, Australia.
    The Long-term Spectral Changes of Eta Carinae: Are they Caused by a Dissipating Occulter as Indicated by CMFGEN Models?2023Ingår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 954Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Eta Carinae (η Car) exhibits a unique set of P Cygni profiles with both broad and narrow components. Over many decades, the spectrum has changed-there has been an increase in observed continuum fluxes and a decrease in Fe II and H I emission-line equivalent widths. The spectrum is evolving toward that of a P Cygni star such as P Cygni itself and HDE 316285. The spectral evolution has been attributed to intrinsic variations such as a decrease in the mass-loss rate of the primary star or differential evolution in a latitudinal-dependent stellar wind. However, intrinsic wind changes conflict with three observational results: the steady long-term bolometric luminosity; the repeating X-ray light curve over the binary period; and the constancy of the dust-scattered spectrum from the Homunculus. We extend previous work that showed a secular strengthening of P Cygni absorptions by adding more orbital cycles to overcome temporary instabilities and by examining more atomic transitions. CMFGEN modeling of the primary wind shows that a time-decreasing mass-loss rate is not the best explanation for the observations. However, models with a small dissipating absorber in our line of sight can explain both the increase in brightness and changes in the emission and P Cygni absorption profiles. If the spectral evolution is caused by the dissipating circumstellar medium, and not by intrinsic changes in the binary, the dynamical timescale to recover from the Great Eruption is much less than a century, different from previous suggestions.

    Ladda ner fulltext (pdf)
    fulltext
  • 5.
    Pickett, Connor S.
    et al.
    Embry Riddle Aeronaut Univ, Dept Phys & Astron, 3700 Willow Creek Rd, Prescott, AZ 86301 USA..
    Richardson, Noel D.
    Embry Riddle Aeronaut Univ, Dept Phys & Astron, 3700 Willow Creek Rd, Prescott, AZ 86301 USA..
    Gull, Theodore R.
    NASA, Exoplanets & Stellar Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.;Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA..
    Hillier, D. John
    Univ Pittsburgh, Dept Phys & Astron, 3941 OHara St, Pittsburgh, PA 15260 USA.;Univ Pittsburgh, Pittsburgh Particle Phys Astrophys & Cosmol Ctr P, 3941 OHara St, Pittsburgh, PA 15260 USA..
    Hartman, Henrik
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Ibrahim, Nour
    Embry Riddle Aeronaut Univ, Dept Phys & Astron, 3700 Willow Creek Rd, Prescott, AZ 86301 USA.;Univ Michigan, Dept Astron, 1085 S Univ, Ann Arbor, MI 48109 USA..
    Lane, Alexis M.
    Embry Riddle Aeronaut Univ, Dept Phys & Astron, 3700 Willow Creek Rd, Prescott, AZ 86301 USA..
    Strawn, Emily
    Embry Riddle Aeronaut Univ, Dept Phys & Astron, 3700 Willow Creek Rd, Prescott, AZ 86301 USA..
    Damineli, Augusto
    Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Rua Matao 1226,Cidade Univ, Sao Paulo, Brazil..
    Moffat, Anthony F. J.
    Univ Montreal, Dept Phys, CP 6128,Succ Ctr Ville, Montreal, PQ H3C 3J7, Canada.;Univ Montreal, Ctr Rech Astrophys Quebec CRAQ, CP 6128,Succ Ctr Ville, Montreal, PQ H3C 3J7, Canada..
    Navarete, Felipe
    SOAR Telescope NSFs NOIRLab, Avda Juan Cisternas 1500, La Serena 1700000, Chile..
    Weigelt, Gerd
    Max Planck Inst Radio Astron, Hugel 69, D-53121 Bonn, Germany..
    Changes in the Na D-1 Absorption Components of eta Carinae Provide Clues on the Location of the Dissipating Central Occulter2022Ingår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 937, nr 2, artikel-id 85Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Na D absorption doublet in the spectrum of eta Carinae is complex, with multiple absorption features associated with the Great Eruption (1840s), the Lesser Eruption (1890s), and the interstellar clouds. The velocity profile is further complicated by the P Cygni profile originating in the system's stellar winds and blending with the He i lambda 5876 profile. The Na D profile contains a multitude of absorption components, including those at velocities of -145 km s(-1), -168 km s(-1), and +87 km s(-1), which we concentrate on in this analysis. Ground-based spectra recorded from 2008 to 2021 show significant variability of the -145 km s(-1) absorption throughout long-term observations. In the high-ionization phases of eta Carinae prior to the 2020 periastron passage, this feature disappeared completely but briefly reappeared across the 2020 periastron, along with a second absorption at -168 km s(-1). Over the past few decades, eta Carinae has been gradually brightening, which is shown to be caused by a dissipating occulter. The decreasing absorption of the -145 km s(-1) component, coupled with similar trends seen in absorptions of ultraviolet resonant lines, indicate that this central occulter was possibly a large clump associated with the Little Homunculus or another clump between the Little Homunculus and the star. We also report on a foreground absorption component at +87 km s(-1). Comparison of Na D absorption in the spectra of nearby systems demonstrates that this redshifted component likely originates in an extended foreground structure consistent with a previous ultraviolet spectral survey in the Carina Nebula.

    Ladda ner fulltext (pdf)
    fulltext
  • 6.
    Gull, Theodore R.
    et al.
    NASA, Goddard Space Flight Ctr, Exoplanets Stellar Astrophys Lab, Greenbelt, MD 20771 USA.;Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA..
    Hillier, D. John
    Univ Pittsburgh, Dept Phys & Astron & Pittsburgh Particle Phys, Phys Astrophys & Cosmol Ctr PITT PACC, 3941 OHara St, Pittsburgh, PA 15260 USA..
    Hartman, Henrik
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Corcoran, Michael F.
    NASA, Goddard Space Flight Ctr, CRESST & Xray Astrophys Lab, Greenbelt, MD 20771 USA.;Catholic Univ Amer, 620 Michigan Ave NE, Washington, DC 20064 USA..
    Damineli, Augusto
    Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Rua Matao 1226, BR-05508090 Sao Paulo, SP, Brazil..
    Espinoza-Galeas, David
    Catholic Univ Amer, 620 Michigan Ave NE, Washington, DC 20064 USA.;Univ Nacl Autonoma Honduras, Fac Ciencias Espaci, Dept Astron Astrofis, Tegucigalpa, Honduras..
    Hamaguchi, Kenji
    Univ Maryland Baltimore Cty, Dept Phys, 1000 Hilltop Circle, Baltimore, MD 21250 USA..
    Navarete, Felipe
    SOAR Telescope NSFs NOIRLab, Avda Juan Cisternas 1500, La Serena 1700000, Chile..
    Nielsen, Krister
    Catholic Univ Amer, 620 Michigan Ave NE, Washington, DC 20064 USA..
    Madura, Thomas
    San Jose State Univ, Dept Phys & Astron, 1 Washington Sq, San Jose, CA 95192 USA..
    Moffat, Anthony F. J.
    Univ Montreal, Dept Phys, CP 6128, Montreal, PQ H3C 3J7, Canada.;Ctr Rech Astrophys Quebec, Quebec City, PQ, Canada..
    Morris, Patrick
    CALTECH, IPAC, M-C 100-22, Pasadena, CA 91125 USA..
    Richardson, Noel D.
    Embry Riddle Aeronaut Univ, Dept Phys Astron, 3700 Willow Creek Rd, Prescott, AZ 86301 USA..
    Russell, Christopher M. P.
    Univ Delaware, Bartol Res Inst, Dept Phys & Astron, Newark, DE 19716 USA..
    Stevens, Ian R.
    Univ Birmingham, Sch Phys & Astron, Birmingham B15 2TT, W Midlands, England..
    Weigelt, Gerd
    Max Planck Inst Radio Astron, Auf Hugel 69, D-53121 Bonn, Germany..
    Eta Carinae: An Evolving View of the Central Binary, Its Interacting Winds and Its Foreground Ejecta2022Ingår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 933, nr 2, s. 1-28, artikel-id 175Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    FUV spectra of eta Car, recorded across two decades with HST/STIS, document multiple changes in resonant lines caused by dissipating extinction in our line of sight. The FUV flux has increased nearly tenfold, which has led to increased ionization of the multiple shells within the Homunculus and photodestruction of H-2. Comparison of observed resonant line profiles with CMFGEN model profiles allows separation of wind-wind collision and shell absorptions from the primary wind P Cygni profiles. The dissipating occulter preferentially obscured the central binary and interacting winds relative to the very extended primary wind. We are now able to monitor changes in the colliding winds with orbital phase. High-velocity transient absorptions occurred across the most recent periastron passage, indicating acceleration of the primary wind by the secondary wind, which leads to a downstream, high-velocity bow shock that is newly generated every orbital period. There is no evidence of changes in the properties of the binary winds.

    Ladda ner fulltext (pdf)
    fulltext
  • 7.
    Gull, Theodore R.
    et al.
    Exoplanets and Stellar Astrophysics Laboratory, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA.
    Navarete, Felipe
    Universidade de São Paulo, IAG, Rua do Matão 1226, Cidade Universitária São Paulo-SP, 05508-090, Brasil.
    Corcoran, Michael F.
    CRESST and X-ray Astrophysics Laboratory, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA ; The Catholic University of America, 620 Michigan Avenue N.E., Washington, DC 20064, USA.
    Damineli, Augusto
    Universidade de São Paulo, IAG, Rua do Matão 1226, Cidade Universitária São Paulo-SP, 05508-090, Brasil.
    Espinoza, David
    CRESST and X-ray Astrophysics Laboratory, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA.
    Hamaguchi, Kenji
    CRESST and X-ray Astrophysics Laboratory, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA; Department of Physics, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
    Hartman, Henrik
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Hillier, D. John
    Department of Physics and Astronomy & Pittsburgh Particle Physics, Astrophysics, and Cosmology Center (PITT PACC), University of Pittsburgh, 3941 O'Hara Street, Pittsburgh, PA 15260, USA.
    Madura, Thomas
    Department of Physics and Astronomy, San Jose State University, One Washington Square, San Jose, CA 95192, USA.
    Moffat, Anthony F. J.
    Département de physique, Université de Montréal, C.P. 6128, Succ. C-V, Montréal, QC H3C 3J7, Canada; Centre de Recherche en Astrophysique du Québec, Canada.
    Morris, Patrick
    California Institute of Technology, IPAC, M/C 100-22, Pasadena, CA 91125, USA.
    Nielsen, Krister
    The Catholic University of America, 620 Michigan Avenue N.E., Washington, DC 20064, USA.
    Pittard, Julian M.
    School of Physics and Astronomy, The University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK.
    Pollock, Andrew M. T.
    Department of Physics and Astronomy, University of Sheffield, Hounsfield Road, Sheffield S3 7RH, UK.
    Richardson, Noel D.
    Department of Physics and Astronomy, Embry-Riddle Aeronautical University, 3700 Willow Creek Road, Prescott, AZ 86301, USA.
    Russell, Christopher M. P.
    CRESST and X-ray Astrophysics Laboratory, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA ; The Catholic University of America, 620 Michigan Avenue N.E., Washington, DC 20064, USA.
    Stevens, Ian R.
    School of Physics & Astronomy, University of Birmingham, Birmingham B15 2TT, UK.
    Weigelt, Gerd
    Max Planck Institute for Radio Astronomy, Auf dem Hügel 69, D-53121 Bonn, Germany.
    Eta Carinae: A Tale of Two Periastron Passages2021Ingår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 923, nr 1, s. 102-102Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Since 2002, the far-ultraviolet (FUV) flux (1150–1680 Å) of Eta Carinae, monitored by the Hubble Space Telescope/Space Telescope Imaging Spectrograph, has increased by an order of magnitude. This increase is attributed to partial dissipation of a line-of-sight (LOS) occulter that blocks the central core of the system. Across the 2020 February periastron passage, changes in the FUV emission show a stronger wavelength dependence than occurred across the 2003 July periastron passage. Across both periastron passages, most of the FUV spectrum dropped in flux then recovered a few months later. The 2020 periastron passage included enhancements of FUV flux in narrow spectral intervals near periastron followed by a transient absorption and recovery to pre-periastron flux levels. The drop in flux is due to increased absorption by singly ionized species as the secondary star plunges deep into the wind of the primary star, which blocks the companion's ionizing radiation. The enhanced FUV emission is caused by the companion's wind-blown cavity briefly opening a window to deeper layers of the primary star. This is the first time transient brightening has been seen in the FUV comparable to transients previously seen at longer wavelengths. Changes in resonance line-velocity profiles hint that the dissipating occulter is associated with material in LOS moving at −100 to −300 km s−1, similar in velocity of structures previously associated with the 1890s lesser eruption

  • 8.
    Hartman, Henrik
    et al.
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM). Lund Observatory.
    Burheim, Madeleine
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM). Lund Observatory.
    Nilsson, Hampus
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM). Lund Observatory.
    Li, Wenxian
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Jönsson, Per
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Laboratory Atomic Astrophysics for near-infrared Stellar Spectroscopy2021Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Astronomical infrared observations are of increasing importance for stellar spectroscopy. The analysis of element abundance relies on high-quality observations, stellar models, and ultimately on accurate atomic data. With the growing number of near-IR astronomical observations and surveys, the absence of highaccuracy data is becoming apparent and a severe limiting factor.We run a program to take up the task to provide evaluated, high-accuracy atomic data for important transitions in the near-infrared spectral region, mainly 1-5 microns. A combinations of both experimental and theoretical techniques is used, to provide complete sets of data with a low uncertainty. FTS measurements of a discharge are combined with laser induced fluorescence techniques, and GRASP2k and ATSP2k atomic structure calculations for the theoretical values.

  • 9.
    Weigelt, G.
    et al.
    Max Planck Inst Radio Astron, Hugel 69, D-53121 Bonn, Germany..
    Hofmann, K. -H
    Max Planck Inst Radio Astron, Hugel 69, D-53121 Bonn, Germany..
    Schertl, D.
    Max Planck Inst Radio Astron, Hugel 69, D-53121 Bonn, Germany..
    Lopez, B.
    Univ Cote dAzur, CNRS, Observatoire Cote dAzur, Lab Lagrange, Blvd lObservatoire,CS 34229, F-06304 Nice 4, France..
    Petrov, R. G.
    Univ Cote dAzur, CNRS, Observatoire Cote dAzur, Lab Lagrange, Blvd lObservatoire,CS 34229, F-06304 Nice 4, France..
    Lagarde, S.
    Univ Cote dAzur, CNRS, Observatoire Cote dAzur, Lab Lagrange, Blvd lObservatoire,CS 34229, F-06304 Nice 4, France..
    Berio, Ph.
    Univ Cote dAzur, CNRS, Observatoire Cote dAzur, Lab Lagrange, Blvd lObservatoire,CS 34229, F-06304 Nice 4, France..
    Jaffe, W.
    Leiden Univ, Leiden Observ, Niels Bohrweg 2, NL-2333 CA Leiden, Netherlands..
    Henning, Th.
    Max Planck Inst Astron, Konigstuhl 17, Heidelberg, Germany..
    Millour, F.
    Univ Cote dAzur, CNRS, Observatoire Cote dAzur, Lab Lagrange, Blvd lObservatoire,CS 34229, F-06304 Nice 4, France..
    Meilland, A.
    Univ Cote dAzur, CNRS, Observatoire Cote dAzur, Lab Lagrange, Blvd lObservatoire,CS 34229, F-06304 Nice 4, France..
    Allouche, F.
    Univ Cote dAzur, CNRS, Observatoire Cote dAzur, Lab Lagrange, Blvd lObservatoire,CS 34229, F-06304 Nice 4, France..
    Robbe-Dubois, S.
    Univ Cote dAzur, CNRS, Observatoire Cote dAzur, Lab Lagrange, Blvd lObservatoire,CS 34229, F-06304 Nice 4, France..
    Matter, A.
    Univ Cote dAzur, CNRS, Observatoire Cote dAzur, Lab Lagrange, Blvd lObservatoire,CS 34229, F-06304 Nice 4, France..
    Cruzalebes, P.
    Univ Cote dAzur, CNRS, Observatoire Cote dAzur, Lab Lagrange, Blvd lObservatoire,CS 34229, F-06304 Nice 4, France..
    Hillier, D. J.
    Univ Pittsburgh, Cosmol Ctr PITT PACC, 3941 OHara St, Pittsburgh, PA 15260 USA.;Univ Pittsburgh, Dept Phys & Astron & Pittsburgh Particle Phys Ast, 3941 OHara St, Pittsburgh, PA 15260 USA..
    Russell, C. M. P.
    Catholic Univ Amer, Inst Astrophys & Computat Sci, 620 Michigan Ave.,N.E, Washington, DC 20064 USA..
    Madura, T.
    San Jose State Univ, Dept Phys & Astron, 1 Washington Sq, San Jose, CA 95192 USA..
    Gull, T. R.
    NASA GSFC, Astrophys Sci Div, Greenbelt, MD 20771 USA..
    Corcoran, M. F.
    Catholic Univ Amer, Inst Astrophys & Computat Sci, 620 Michigan Ave.,N.E, Washington, DC 20064 USA.;NASA GSFC, CRESST II & Xray Astrophys Lab, Greenbelt, MD 20771 USA..
    Damineli, A.
    Univ Sao Paulo, Inst Astron Geofis Ciencias Atmosfer, Rua Matao 1226,Cidade Univ, BR-05508090 Sao Paulo, SP, Brazil..
    Moffat, A. F. J.
    Univ Montreal, Ctr Rech Astrophys Quebec CRAQ, CP 6128 Succ. A.,Centre Ville, Montreal, PQ H3C 3J7, Canada..
    Morris, P. W.
    Univ Montreal, Dept Phys, CP 6128 Succ. A.,Centre Ville, Montreal, PQ H3C 3J7, Canada..
    Richardson, N. D.
    IPAC, Calif Inst Technol, M C 100-22, Pasadena, CA 91125 USA..
    Paladini, C.
    Embry Riddle Aeronaut Univ, Dept Phys & Astron, 3700 Willow Creek Rd, Prescott, AZ 86301 USA..
    Schoeller, M.
    European Southern Observ, 19001 Santiago 19, Chile..
    Merand, A.
    European Southern Observ, 19001 Santiago 19, Chile..
    Glindemann, A.
    European Southern Observ, 19001 Santiago 19, Chile..
    Beckmann, U.
    Max Planck Inst Radio Astron, Hugel 69, D-53121 Bonn, Germany..
    Heininger, M.
    Max Planck Inst Radio Astron, Hugel 69, D-53121 Bonn, Germany..
    Bettonvil, F.
    Leiden Univ, Leiden Observ, Niels Bohrweg 2, NL-2333 CA Leiden, Netherlands.
    Zins, G.
    Embry Riddle Aeronaut Univ, Dept Phys & Astron, 3700 Willow Creek Rd, Prescott, AZ 86301 USA.
    Woillez, J.
    European Southern Observ, 19001 Santiago 19, Chile..
    Bristow, P.
    European Southern Observ, 19001 Santiago 19, Chile..
    Sanchez-Bermudez, J.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Garching, Germany..
    Ohnaka, K.
    Univ Nacl Autonoma Mexico, Inst Astron, Apdo. Postal 70264, Mexico City, DF 04510, Mexico..
    Kraus, S.
    Univ Andres Bello, Fac Ciencias Exactas, Dept Ciencias Fis, Fernandez Concha 700, Santiago, Chile..
    Mehner, A.
    Embry Riddle Aeronaut Univ, Dept Phys & Astron, 3700 Willow Creek Rd, Prescott, AZ 86301 USA.
    Wittkowski, M.
    European Southern Observ, 19001 Santiago 19, Chile.
    Hummel, C. A.
    European Southern Observ, 19001 Santiago 19, Chile.
    Stee, P.
    Univ Cote dAzur, CNRS, Observatoire Cote dAzur, Lab Lagrange, Blvd lObservatoire,CS 34229, F-06304 Nice 4, France..
    Vakili, F.
    Univ Cote dAzur, CNRS, Observatoire Cote dAzur, Lab Lagrange, Blvd lObservatoire,CS 34229, F-06304 Nice 4, France..
    Hartman, Henrik
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Navarete, F.
    Univ Sao Paulo, Inst Astron Geofis Ciencias Atmosfer, Rua Matao 1226,Cidade Univ, BR-05508090 Sao Paulo, SP, Brazil.
    Hamaguchi, K.
    NASA GSFC, CRESST II & Xray Astrophys Lab, Greenbelt, MD 20771 USA; Univ Maryland, Dept Phys, Baltimore Cty,1000 Hilltop Circle, Baltimore, MD 21250 USA.
    Espinoza-Galeas, D. A.
    NASA GSFC, CRESST II & Xray Astrophys Lab, Greenbelt, MD 20771 USA.
    Stevens, I. R.
    Univ Maryland, Dept Phys, Baltimore Cty,1000 Hilltop Circle, Baltimore, MD 21250 USA..
    van Boekel, R.
    Max Planck Inst Astron, Konigstuhl 17, Heidelberg, Germany.
    Wolf, S.
    Univ Birmingham, Sch Phys & Astron, Birmingham B15 2TT, W Midlands, England..
    Hogerheijde, M. R.
    Leiden Univ, Leiden Observ, Niels Bohrweg 2, NL-2333 CA Leiden, Netherlands.;Univ Kiel, Inst Theoret Phys & Astrophys, Leibnizstrasse 15, D-24118 Kiel, Germany..
    Dominik, C.
    Univ Kiel, Inst Theoret Phys & Astrophys, Leibnizstrasse 15, D-24118 Kiel, Germany..
    Augereau, J. -C
    Univ Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble, France.
    Pantin, E.
    Univ Paris Diderot, Univ Paris Saclay, CNRS, CEA,AIM, Sorbonne Paris Cite, F-91191 Gif Sur Yvette, France.
    Waters, L. B. F. M.
    Univ Paris Diderot, Univ Paris Saclay, CNRS, CEA,AIM, Sorbonne Paris Cite, F-91191 Gif Sur Yvette, France.;Radboud Univ Nijmegen, Inst Math Astrophys & Particle Phys, Box 9010, NL-MC626500 Nijmegen, Netherlands..
    Meisenheimer, K.
    Max Planck Inst Astron, Konigstuhl 17, Heidelberg, Germany.
    Varga, J.
    Leiden Univ, Leiden Observ, Niels Bohrweg 2, NL-2333 CA Leiden, Netherlands.;Univ Vienna, Dept Astrophys, Turkenschanzstrasse 17, A-1180 Vienna, Austria..
    Klarmann, L.
    Max Planck Inst Astron, Konigstuhl 17, Heidelberg, Germany.
    Gamez Rosas, V.
    Leiden Univ, Leiden Observ, Niels Bohrweg 2, NL-2333 CA Leiden, Netherlands..
    Burtscher, L.
    Leiden Univ, Leiden Observ, Niels Bohrweg 2, NL-2333 CA Leiden, Netherlands..
    Leftley, J.
    Univ Cote dAzur, CNRS, Observatoire Cote dAzur, Lab Lagrange, Blvd lObservatoire,CS 34229, F-06304 Nice 4, France..
    Isbell, J. W.
    Max Planck Inst Astron, Konigstuhl 17, Heidelberg, Germany..
    Hocde, V.
    Univ Cote dAzur, CNRS, Observatoire Cote dAzur, Lab Lagrange, Blvd lObservatoire,CS 34229, F-06304 Nice 4, France..
    Yoffe, G.
    Max Planck Inst Astron, Konigstuhl 17, Heidelberg, Germany..
    Kokoulina, E.
    Univ Cote dAzur, CNRS, Observatoire Cote dAzur, Lab Lagrange, Blvd lObservatoire,CS 34229, F-06304 Nice 4, France..
    Hron, J.
    Radboud Univ Nijmegen, Inst Math Astrophys & Particle Phys, Box 9010, NL-MC626500 Nijmegen, Netherlands..
    Groh, J.
    SRON Netherlands Inst Space Res, Sorbonnelaan 2, NL-3584 CA Utrecht, Netherlands..
    Kreplin, A.
    Univ Exeter, Sch Phys, Astrophys Grp, Stocker Rd, Exeter EX4 4QL, Devon, England.
    Rivinius, Th.
    European Southern Observ, 19001 Santiago 19, Chile.
    de Wit, W. -J
    European Southern Observ, 19001 Santiago 19, Chile.
    Danchi, W. -C
    Univ Cote dAzur, CNRS, Observatoire Cote dAzur, Lab Lagrange, Blvd lObservatoire,CS 34229, F-06304 Nice 4, France; NASA GSFC, Astrophys Sci Div, Greenbelt, MD 20771 USA.
    Domiciano de Souza, A.
    Univ Cote dAzur, CNRS, Observatoire Cote dAzur, Lab Lagrange, Blvd lObservatoire,CS 34229, F-06304 Nice 4, France..
    Drevon, J.
    Univ Cote dAzur, CNRS, Observatoire Cote dAzur, Lab Lagrange, Blvd lObservatoire,CS 34229, F-06304 Nice 4, France..
    Labadie, L.
    Univ Dublin, Trin Coll Dublin, Dublin, Ireland.;Res Ctr Astron & Earth Sci, Konkoly Observ, Konkoly Thege Miklosut 15-17, H-1121 Budapest, Hungary.;Univ Cologne, Physikal Inst 1, Zulpicher Str. 77, D-50937 Cologne, Germany..
    Connot, C.
    Max Planck Inst Radio Astron, Hugel 69, D-53121 Bonn, Germany..
    Nussbaum, E.
    Max Planck Inst Radio Astron, Hugel 69, D-53121 Bonn, Germany..
    Lehmitz, M.
    Max Planck Inst Astron, Konigstuhl 17, Heidelberg, Germany.
    Antonelli, P.
    Univ Cote dAzur, CNRS, Observatoire Cote dAzur, Lab Lagrange, Blvd lObservatoire,CS 34229, F-06304 Nice 4, France..
    Graser, U.
    Max Planck Inst Astron, Konigstuhl 17, Heidelberg, Germany..
    Leinert, C.
    Max Planck Inst Astron, Konigstuhl 17, Heidelberg, Germany..
    VLTI-MATISSE chromatic aperture-synthesis imaging of eta Carinae's stellar wind across the Br alpha line Periastron passage observations in February 20202021Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 652, artikel-id A140Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Context. Eta Carinae is a highly eccentric, massive binary system (semimajor axis similar to 15.5 au) with powerful stellar winds and a phase-dependent wind-wind collision (WWC) zone. The primary star, eta Car A, is a luminous blue variable (LBV); the secondary, eta Car B, is a Wolf-Rayet or O star with a faster but less dense wind. Aperture-synthesis imaging allows us to study the mass loss from the enigmatic LBV eta Car. Understanding LBVs is a crucial step toward improving our knowledge about massive stars and their evolution. Aims. Our aim is to study the intensity distribution and kinematics of eta Car's WWC zone. Methods. Using the VLTI-MATISSE mid-infrared interferometry instrument, we perform Br alpha imaging of eta Car's distorted wind. Results. We present the first VLTI-MATISSE aperture-synthesis images of eta Car A's stellar windin several spectral channels distributed across the Br alpha 4.052 mu m line (spectral resolving power R similar to 960). Our observations were performed close to periastron passage in February 2020 (orbital phase similar to 14.0022). The reconstructed iso-velocity images show the dependence of the primary stellar wind on wavelength or line-of-sight (LOS) velocity with a spatial resolution of 6 mas (similar to 14 au). The radius of the faintest outer wind regions is similar to 26 mas (similar to 60 au). At several negative LOS velocities, the primary stellar wind is less extended to the northwest than in other directions. This asymmetry is most likely caused by the WWC. Therefore, we see both the velocity field of the undisturbed primary wind and the WWC cavity. In continuum spectral channels, the primary star wind is more compact than in line channels. A fit of the observed continuum visibilities with the visibilities of a stellar wind CMFGEN model (CMFGEN is an atmosphere code developed to model the spectra of a variety of objects) provides a full width at half maximum fit diameter of the primary stellar wind of 2.84 +/- 0.06 mas (6.54 +/- 0.14 au). We comparethe derived intensity distributions with the CMFGEN stellar wind model and hydrodynamic WWC models.

    Ladda ner fulltext (pdf)
    fulltext
  • 10.
    Li, Wenxian
    et al.
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Rynkun, P.
    Institute of Theoretical Physics and Astronomy, Vilnius University, Saulėtekio Av. 3, Vilnius, 10222, Lithuania.
    Radziute, L.
    Institute of Theoretical Physics and Astronomy, Vilnius University, Saulėtekio Av. 3, Vilnius, 10222, Lithuania.
    Gaigalas, G.
    Institute of Theoretical Physics and Astronomy, Vilnius University, Saulėtekio Av. 3, Vilnius, 10222, Lithuania.
    Atalay, B.
    Division of Mathematical Physics, Lund University, Post Office Box 118, Lund, 22100, Sweden; Department of Physics, Çanakkale Onsekiz Mart University, Çanakkale, Turkey;.
    Papoulia, Asimina
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM). Division of Mathematical Physics, Lund University, Post Office Box 118, Lund, 22100, Sweden.
    Wang, K.
    Hebei Key Lab of Optic-electronic Information and Materials, College of Physics Science and Technology, Hebei University, Baoding, 071002, China.
    Hartman, Henrik
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Ekman, Jörgen
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Brage, T.
    Division of Mathematical Physics, Lund University, Post Office Box 118, Lund, 22100, Sweden.
    Chen, C. Y.
    Shanghai Ebit Lab, Key Laboratory of Nuclear Physics and Ion-beam Application, Institute of Modern Physics, Department of Nuclear Science and Technology, Fudan University, Shanghai, 200433, China.
    Jönsson, Per
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (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 II2020Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 639, artikel-id A25Artikel i tidskrift (Refereegranskat)
    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.

  • 11.
    Schmidt, H. T.
    et al.
    Stockholm University, Department of Physics, Stockholm, 10691, Sweden.
    Rosen, S.
    Stockholm University, Department of Physics, Stockholm, 10691, Sweden.
    Thomas, R. D.
    Stockholm University, Department of Physics, Stockholm, 10691, Sweden.
    Stockett, M. H.
    Stockholm University, Department of Physics, Stockholm, 10691, Sweden.
    Geppert, W. D.
    Stockholm University, Department of Physics, Stockholm, 10691, Sweden.
    Larson, A.
    Stockholm University, Department of Physics, Stockholm, 10691, Sweden.
    Löfgren, P.
    Stockholm University, Department of Physics, Stockholm, 10691, Sweden.
    Simonsson, A.
    Stockholm University, Department of Physics, Stockholm, 10691, Sweden.
    Källberg, A.
    Stockholm University, Department of Physics, Stockholm, 10691, Sweden.
    Reinhed, P.
    Stockholm University, Department of Physics, Stockholm, 10691, Sweden.
    Björkhage, M.
    Stockholm University, Department of Physics, Stockholm, 10691, Sweden.
    Blom, M.
    Stockholm University, Department of Physics, Stockholm, 10691, Sweden.
    Alexander, J. D.
    Stockholm University, Department of Physics, Stockholm, 10691, Sweden.
    Najeeb, P. K.
    Stockholm University, Department of Physics, Stockholm, 10691, Sweden.
    Ji, M.
    Stockholm University, Department of Physics, Stockholm, 10691, Sweden.
    Kono, N.
    Stockholm University, Department of Physics, Stockholm, 10691, Sweden.
    Anderson, E. K.
    Stockholm University, Department of Physics, Stockholm, 10691, Sweden.
    Eklund, G.
    Stockholm University, Department of Physics, Stockholm, 10691, Sweden.
    Kristiansson, M. K.
    Stockholm University, Department of Physics, Stockholm, 10691, Sweden.
    Hole, O. M.
    Stockholm University, Department of Physics, Stockholm, 10691, Sweden.
    Hanstorp, D.
    University of Gothenburg, Department of Physics, Gothenburg, 41296, Sweden.
    Hartman, Henrik
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Barklem, P. S.
    Uppsala University, Department of Physics and Astronomy, Uppsala, 75236, Sweden.
    Grumer, J.
    Uppsala University, Department of Physics and Astronomy, Uppsala, 75236, Sweden.
    Hansen, K.
    University of Gothenburg, Department of Physics, Gothenburg, 41296, Sweden; Tianjin University, Department of Physics, Tianjin, 300072, China.
    Gatchell, M.
    Stockholm University, Department of Physics, Stockholm, 10691, Sweden; Universität Innsbruck, Institut für Ionenphysik und Angewandte Physik, Innsbruck, 6020, Austria.
    Cederquist, H.
    Stockholm University, Department of Physics, Stockholm, 10691, Sweden.
    Zettergren, H.
    Stockholm University, Department of Physics, Stockholm, 10691, Sweden.
    Negative ion relaxation and reactions in a cryogenic storage ring2020Ingår i: 31st International Conference on Photonic, Electronic and Atomic Collisions (ICPEAC XXXI) / [ed] Ancarani, LU Bordas, C Lepine, F Vernhet, D Bachau, H Bredy, R Dulieu, O Penent, F, Institute of Physics Publishing (IOPP), 2020, artikel-id 062006Konferensbidrag (Refereegranskat)
    Abstract [en]

    An overview of recent experimental results of studies of negative atomic and molecular ions in the Double ElectroStatic Ion-Ring ExpEriment, DESIREE is given. Metastable level lifetimes in atomic negative ions have been measured by time-dependent laser photodetachment. Rotational relaxation of diatomic anions is studied by near-threshold photodetachment. Spontaneous decays of small metal cluster anions by electron emission and fragmentation is studied with decay-channel specificity. Finally, mutual neutralisation of pairs of negative and positive ions has been investigated with initial and final state selectivity.

    Ladda ner fulltext (pdf)
    fulltext
  • 12.
    Vanzella, E.
    et al.
    INAF - Osservatorio di Astrofisica e Scienza dello Spazio, via Gobetti 93/3, Bologna, I-40129, Italy.
    Meneghetti, M.
    INAF - Osservatorio di Astrofisica e Scienza dello Spazio, via Gobetti 93/3, Bologna, I-40129, Italy.
    Pastorello, A.
    INAF - Osservatorio Astronomico di Padova, Vicolo Osservatorio 5, Padova, I-35122, Italy.
    Calura, F.
    INAF - Osservatorio di Astrofisica e Scienza dello Spazio, via Gobetti 93/3, Bologna, I-40129, Italy.
    Sani, E.
    European Southern Observatory, Alonso de Cordova 3107, Casilla, Santiago, 19001, Chile.
    Cupani, G.
    INAF - Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, Trieste, I-34143, Italy.
    Caminha, G. B.
    Kapteyn Astronomical Institute, University of Groningen, Postbus 800, Groningen, NL-9700, Netherlands.
    Castellano, M.
    INAF - Osservatorio Astronomico di Roma, Via Frascati 33, Monte Porzio Catone, I-00078, Italy.
    Rosati, P.
    INAF - Osservatorio di Astrofisica e Scienza dello Spazio, via Gobetti 93/3, Bologna, I-40129, Italy; Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Ferrara, via Saragat 1, Ferrara, I-44122, Italy.
    D’Odorico, V.
    INAF - Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, Trieste, I-34143, Italy.
    Cristiani, S.
    INAF - Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, Trieste, I-34143, Italy.
    Grillo, C.
    Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, Milano, I-20133, Italy.
    Mercurio, A.
    INAF – Osservatorio Astronomico di Capodimonte, Via Moiariello 16, I-80131 Napoli, Italy.
    Nonino, M.
    INAF - Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, Trieste, I-34143, Italy.
    Brammer, G. B.
    Cosmic Dawn Center, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, Copenhagen, DK-2100, Denmark.
    Hartman, Henrik
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Probing the circumstellar medium 2.8 Gyr after the big bang: detection of Bowen fluorescence in the Sunburst arc2020Ingår i: Monthly Notices of the Royal Astronomical Society: Letters, ISSN 1745-3925, Vol. 499, nr 1, s. L67-L71Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We discovered Bowen emission arising from a strongly lensed (i.e., with magnification factor μ>20) source hosted in the Sunburst arc at z=2.37. We claim this source is plausibly a transient stellar object and study the unique ultraviolet lines emerging from it. In particular, narrow (σ_v ~ 40 km/s) ionisation lines of Fe fluoresce after being exposed to Lya radiation that pumps selectively their atomic levels. Data from VLT/MUSE, X-Shooter and ESPRESSO observations (the latter placed at the focus of the four UTs) at increasing spectral resolution of R=2500, 11400 and R=70000, respectively, confirm such fluorescent lines are present since at least 3.3 years (~ 1 year rest-frame). Additional Fe forbidden lines have been detected, while C and Si doublets probe an electron density n_e >~ 106 cm−3. Similarities with the spectral features observed in the circum-stellar Weigelt blobs of Eta-Carinae probing the circum-stellar dense gas condensations in radiation-rich conditions are observed. We discuss the physical origin of the transient event, which remains unclear. We expect such transient events (including also supernova or impostors) will be easily recognised with ELTs thanks to high angular resolution provided by adaptive optics and large collecting area, especially in modest (μ<3) magnification regime.

  • 13.
    Li, Wenxian
    et al.
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Hartman, Henrik
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Wang, Kai
    Hebei Key Lab of Optic-electronic Information and Materials, The College of Physics Science and Technology, Hebei University,.
    Jönsson, Per
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Theoretical investigation of oscillator strengths and lifetimes inTi ii2020Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 643, s. 1-14, artikel-id A156Artikel i tidskrift (Refereegranskat)
    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.

    Ladda ner fulltext (pdf)
    fulltext
  • 14. de Jong, R. S.
    et al.
    Agertz, O.
    Berbel, A. A.
    Aird, J.
    Alexander, D. A.
    Amarsi, A.
    Anders, F.
    Andrae, R.
    Ansarinejad, B.
    Ansorge, W.
    Antilogus, P.
    Anwand -Heerwart, H.
    Arentsen, A.
    Arnadottir, A.
    Asplund, M.
    Auger, M.
    Azais, N.
    Baade, D.
    Baker, G.
    Baker, S.
    Balbinot, E.
    Baldry, I. K.
    Banerji, M.
    Barden, S.
    Barklem, P.
    Barthélémy-Mazot, E.
    Battistini, C.
    Bauer, S.
    Bell, C. P. M.
    Bellido-Tirado, O.
    Bellstedt, S.
    Belokurov, V.
    Bensby, T.
    Bergemann, M.
    Bestenlehner, J. M.
    Bielby, R.
    Bilicki, M.
    Blake, C.
    Bland-Hawthorn, J.
    Boeche, C.
    Boland, W.
    Boller, T.
    Bongard, S.
    Bongiorno, A.
    Bonifacio, P.
    Boudon, D.
    Brooks, D.
    Brown, M. J. I.
    Brown, R.
    Brüggen, M.
    Brynnel, J.
    Brzeski, J.
    Buchert, T.
    Buschkamp, P.
    Caffau, E.
    Caillier, P.
    Carrick, J.
    Casagrande, L.
    Case, S.
    Casey, A.
    Cesarini, I.
    Cescutti, G.
    Chapuis, D.
    Chiappini, C.
    Childress, M.
    Christlieb, N.
    Church, R.
    Cioni, M. -RL.
    Cluver, M.
    Colless, M.
    Collett, T.
    Comparat, J.
    Cooper, A.
    Couch, W.
    Courbin, F.
    Croom, S.
    Croton, D.
    Daguisé, E.
    Dalton, G.
    Davies, L. J. M.
    Davis, T.
    de Laverny, P.
    Deason, A.
    Dionies, F.
    Disseau, K.
    Doel, P.
    Döscher, D.
    Driver, S. P.
    Dwelly, T.
    Eckert, D.
    Edge, A.
    Edvardsson, B.
    Youssoufi, D. E.
    Elhaddad, A.
    Enke, H.
    Erfanianfar, G.
    Farrell, T.
    Fechner, T.
    Feiz, C.
    Feltzing, S.
    Ferreras, I.
    Feuerstein, D.
    Feuillet, D.
    Finoguenov, A.
    Ford, D.
    Fotopoulou, S.
    Fouesneau, M.
    Frenk, C.
    Frey, S.
    Gaessler, W.
    Geier, S.
    Fusillo, N. G.
    Gerhard, O.
    Giannantonio, T.
    Giannone, D.
    Gibson, B.
    Gillingham, P.
    González-Fernández, C.
    Gonzalez-Solares, E.
    Gottloeber, S.
    Gould, A.
    Grebel, E. K.
    Gueguen, A.
    Guiglion, G.
    Haehnelt, M.
    Hahn, T.
    Hansen, C. J.
    Hartman, Henrik
    Lund Observatory, Lund University, Sweden.
    Hauptner, K.
    Hawkins, K.
    Haynes, D.
    Haynes, R.
    Heiter, U.
    Helmi, A.
    Aguayo, C. H.
    Hewett, P.
    Hinton, S.
    Hobbs, D.
    Hoenig, S.
    Hofman, D.
    Hook, I.
    Hopgood, J.
    Hopkins, A.
    Hourihane, A.
    Howes, L.
    Howlett, C.
    Huet, T.
    Irwin, M.
    Iwert, O.
    Jablonka, P.
    Jahn, T.
    Jahnke, K.
    Jarno, A.
    Jin, S.
    Jofre, P.
    Johl, D.
    Jones, D.
    Jönsson, Henrik
    Lund Observatory, Lund University, Sweden.
    Jordan, C.
    Karovicova, I.
    Khalatyan, A.
    Kelz, A.
    Kennicutt, R.
    King, D.
    Kitaura, F.
    Klar, J.
    Klauser, U.
    Kneib, J. -P
    Koch, A.
    Koposov, S.
    Kordopatis, G.
    Korn, A.
    Kosmalski, J.
    Kotak, R.
    Kovalev, M.
    Kreckel, K.
    Kripak, Y.
    Krumpe, M.
    Kuijken, K.
    Kunder, A.
    Kushniruk, I.
    Lam, M. I.
    Lamer, G.
    Laurent, F.
    Lawrence, J.
    Lehmitz, M.
    Lemasle, B.
    Lewis, J.
    Li, B.
    Lidman, C.
    Lind, K.
    Liske, J.
    Lizon, J. -L
    Loveday, J.
    Ludwig, H. -G
    McDermid, R. M.
    Maguire, K.
    Mainieri, V.
    Mali, S.
    Mandel, H.
    Mandel, K.
    Mannering, L.
    Martell, S.
    Martinez Delgado, D.
    Matijevic, G.
    McGregor, H.
    McMahon, R.
    McMillan, P.
    Mena, O.
    Merloni, A.
    Meyer, M. J.
    Michel, C.
    Micheva, G.
    Migniau, J. -E
    Minchev, I.
    Monari, G.
    Muller, R.
    Murphy, D.
    Muthukrishna, D.
    Nandra, K.
    Navarro, R.
    Ness, M.
    Nichani, V.
    Nichol, R.
    Nicklas, H.
    Niederhofer, F.
    Norberg, P.
    Obreschkow, D.
    Oliver, S.
    Owers, M.
    Pai, N.
    Pankratow, S.
    Parkinson, D.
    Paschke, J.
    Paterson, R.
    Pecontal, A.
    Parry, I.
    Phillips, D.
    Pillepich, A.
    Pinard, L.
    Pirard, J.
    Piskunov, N.
    Plank, V.
    Plüschke, D.
    Pons, E.
    Popesso, P.
    Power, C.
    Pragt, J.
    Pramskiy, A.
    Pryer, D.
    Quattri, M.
    Queiroz, A. B. d. A.
    Quirrenbach, A.
    Rahurkar, S.
    Raichoor, A.
    Ramstedt, S.
    Rau, A.
    Recio-Blanco, A.
    Reiss, R.
    Renaud, F.
    Revaz, Y.
    Rhode, P.
    Richard, J.
    Richter, A. D.
    Rix, H. -W
    Robotham, A. S. G.
    Roelfsema, R.
    Romaniello, M.
    Rosario, D.
    Rothmaier, F.
    Roukema, B.
    Ruchti, G.
    Rupprecht, G.
    Rybizki, J.
    Ryde, N.
    Saar, A.
    Sadler, E.
    Sahlén, M.
    Salvato, M.
    Sassolas, B.
    Saunders, W.
    Saviauk, A.
    Sbordone, L.
    Schmidt, T.
    Schnurr, O.
    Scholz, R. -D
    Schwope, A.
    Seifert, W.
    Shanks, T.
    Sheinis, A.
    Sivov, T.
    Skúladóttir, Á.
    Smartt, S.
    Smedley, S.
    Smith, G.
    Smith, R.
    Sorce, J.
    Spitler, L.
    Starkenburg, E.
    Steinmetz, M.
    Stilz, I.
    Storm, J.
    Sullivan, M.
    Sutherland, W.
    Swann, E.
    Tamone, A.
    Taylor, E. N.
    Teillon, J.
    Tempel, E.
    ter Horst, R.
    Thi, W. -F
    Tolstoy, E.
    Trager, S.
    Traven, G.
    Tremblay, P. -E
    Tresse, L.
    Valentini, M.
    van de Weygaert, R.
    van den Ancker, M.
    Veljanoski, J.
    Venkatesan, S.
    Wagner, L.
    Wagner, K.
    Walcher, C. J.
    Waller, L.
    Walton, N.
    Wang, L.
    Winkler, R.
    Wisotzki, L.
    Worley, C. C.
    Worseck, G.
    Xiang, M.
    Xu, W.
    Yong, D.
    Zhao, C.
    Zheng, J.
    Zscheyge, F.
    Zucker, D.
    4MOST: Project overview and information for the First Call for Proposals2019Ingår i: The Messenger, ISSN 0722-6691, Vol. 175, s. 3-11Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    We introduce the 4-metre Multi-Object Spectroscopic Telescope (4MOST), a new high-multiplex, wide-field spectroscopic survey facility under development for the four-metre-class Visible and Infrared Survey Telescope for Astronomy (VISTA) at Paranal. Its key specifications are: a large field of view (FoV) of 4.2 square degrees and a high multiplex capability, with 1624 fibres feeding two low-resolution spectrographs (R = λ/Δλ ~ 6500), and 812 fibres transferring light to the high-resolution spectrograph (R ~ 20 000). After a description of the instrument and its expected performance, a short overview is given of its operational scheme and planned 4MOST Consortium science; these aspects are covered in more detail in other articles in this edition of The Messenger. Finally, the processes, schedules, and policies concerning the selection of ESO Community Surveys are presented, commencing with a singular opportunity to submit Letters of Intent for Public Surveys during the first five years of 4MOST operations.

    Ladda ner fulltext (pdf)
    fulltext
  • 15. Nave, Gillian
    et al.
    Barklem, Paul
    Belmonte, Maria Teresa
    Brickhouse, Nancy
    Butler, Paul
    Cashman, Frances
    Chatzikos, M.
    Cowley, Charles R.
    Den Hartog, Elizabeth
    Federman, Steven
    Ferland, Gary
    Fogle, Michael
    Hartman, Henrik
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Guzman, Francisco
    Heap, Sara
    Kerber, Florian
    Kramida, Alexander
    Kulkarni, Varsha P.
    Lawler, James E.
    Marler, Joan
    Nahar, Sultana
    Pickering, Juliet
    Quinet, Pascal
    Ralchenko, Yuri
    Savin, Daniel
    Sneden, Chris
    Takacs, Endre
    Wahlgren, Glenn
    Webb, John
    Wiseman, Jennifer
    Wood, Mike
    Atomic data for astrophysics: Needs and challenges2019Ingår i: Bulletin of the American Astronomical Society, 2019, Vol. 51Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    We describe the impact of atomic spectroscopy on astrophysics and future requirements for atomic data. These requirements cannot be met with current levels of funding for laboratory astrophysics. The situation could be substantially improved with relatively small investment from the funding agencies.

  • 16.
    Papoulia, Asimina
    et al.
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM). Lund Univ, Dept Phys, Div Math Phys, SE-22100 Lund, Sweden..
    Ekman, Jörgen
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Gaigalas, Gediminas
    Vilnius Univ, Inst Theoret Phys & Astron, Sauletekio Av 3, LT-10222 Vilnius, Lithuania..
    Godefroid, Michel
    Univ Libre Bruxelles, Chim Quant & Photophys, B-1050 Brussels, Belgium..
    Gustafsson, Stefan
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Hartman, Henrik
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Li, Wenxian
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Radziute, Laima
    Vilnius Univ, Inst Theoret Phys & Astron, Sauletekio Av 3, LT-10222 Vilnius, Lithuania..
    Rynkun, Pavel
    Vilnius Univ, Inst Theoret Phys & Astron, Sauletekio Av 3, LT-10222 Vilnius, Lithuania..
    Schiffmann, Sacha
    Lund Univ, Dept Phys, Div Math Phys, SE-22100 Lund, Sweden.;Univ Libre Bruxelles, Chim Quant & Photophys, B-1050 Brussels, Belgium..
    Wang, Kai
    Hebei Univ, Coll Phys Sci & Technol, Hebei Key Lab Opt Elect Informat Mat, Baoding 071002, Peoples R China..
    Jönsson, Per
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Coulomb (Velocity) Gauge Recommended in Multiconfiguration Calculations of Transition Data Involving Rydberg Series2019Ingår i: Atoms, E-ISSN 2218-2004, Vol. 7, nr 4, artikel-id 106Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Astronomical spectroscopy has recently expanded into the near-infrared (nIR) wavelength region, raising the demands on atomic transition data. The interpretation of the observed spectra largely relies on theoretical results, and progress towards the production of accurate theoretical data must continuously be made. Spectrum calculations that target multiple atomic states at the same time are by no means trivial. Further, numerous atomic systems involve Rydberg series, which are associated with additional difficulties. In this work, we demonstrate how the challenges in the computations of Rydberg series can be handled in large-scale multiconfiguration Dirac-Hartree-Fock (MCDHF) and relativistic configuration interaction (RCI) calculations. By paying special attention to the construction of the radial orbital basis that builds the atomic state functions, transition data that are weakly sensitive to the choice of gauge can be obtained. Additionally, we show that the Babushkin gauge should not always be considered as the preferred gauge, and that, in the computations of transition data involving Rydberg series, the Coulomb gauge could be more appropriate for the analysis of astrophysical spectra. To illustrate the above, results from computations of transitions involving Rydberg series in the astrophysically important C IV and C III ions are presented and analyzed.

    Ladda ner fulltext (pdf)
    fulltext
  • 17.
    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 universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (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 II2019Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 627, artikel-id A102Artikel i tidskrift (Refereegranskat)
    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.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 18.
    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 universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM). Lund Observatory, Lund University, Box 43, 22100 Lund, Sweden.
    Experimental transition probabilities for 4p-4d spectral lines in V II2019Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 622, artikel-id A154Artikel i tidskrift (Refereegranskat)
    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.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 19.
    Atalay, B.
    et al.
    Department of Physics, Lund University, Post Office Box 118, Lund, 22100, Sweden; Department of Physics, Çanakkale Onsekiz Mart University, Çanakkale, Turkey;.
    Brage, T.
    Department of Physics, Lund University, Post Office Box 118, Lund, 22100, Sweden; Institute of Modern Physics, Fudan University, Shanghai, China.
    Jönsson, Per
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Hartman, Henrik
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    MCDHF and RCI calculations of energy levels, lifetimes, and transition rates in Si III and Si IV2019Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, ISSN 0004-6361, Vol. 631, artikel-id A29Artikel i tidskrift (Refereegranskat)
    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.

  • 20.
    Ryde, N.
    et al.
    Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, Lund, 22100, Sweden.
    Hartman, Henrik
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM). Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43 221 00 Lund, Sweden.
    Oliva, E.
    INAF-Arcetri Astrophysical Observatory, Largo E. Fermi 5, Firenze, 50125, Italy.
    Origlia, L.
    INAF, Osservatorio di Astrofisica e Scienza Dello Spazio di Bologna, Via Gobetti 93/3, Bologna, 40129, Italy.
    Sanna, N.
    INAF-Arcetri Astrophysical Observatory, Largo E. Fermi 5, Firenze, 50125, Italy.
    Rainer, M.
    INAF-Arcetri Astrophysical Observatory, Largo E. Fermi 5, Firenze, 50125, Italy.
    Thorsbro, B.
    Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, Lund, 22100, Sweden.
    Dalessandro, E.
    INAF, Osservatorio di Astrofisica e Scienza Dello Spazio di Bologna, Via Gobetti 93/3, Bologna, 40129, Italy.
    Bono, G.
    Stellar population astrophysics (SPA) with the TNG. Identification of a sulphur line at λ_air = 1063.6 nm in GIANO-B stellar spectra2019Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 631, s. L3-L5Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Context. In the advent of new infrared, high-resolution spectrometers, accurate and precise atomic data in the infrared is urgently needed. Identifications, wavelengths, strengths, broadening and hyper-fine splitting parameters of stellar lines in the near-IR are in many cases not accurate enough to model observed spectra, and in other cases even non existing. Some stellar features are unidentified. Aims. The aim with this work is to identify a spectral feature at lambda(vac) = 1063.891 nm or lambda(air) = 1063.600 nm seen in spectra of stars of different spectral types, observed with the GIANO-B spectrometer. Methods. Searching for spectral lines to match the unidentified feature in linelists from standard atomic databases was not successful. However, by investigating the original, published laboratory data we were able to identify the feature and solve the problem. To confirm its identification, we model the presumed stellar line in the solar intensity spectrum and find an excellent match. Results. We find that the observed spectral feature is a stellar line originating from the 4s'-4p' transition in S I, and that the reason for its absence in atomic line databases is a neglected air-to-vacuum correction in the original laboratory measurements from 1967 for this line only. From interpolation we determine the laboratory wavelength of the S I line to be lambda(vac) = 1063.8908 nm or lambda(air) = 1063.5993 nm, and the excitation energy of the upper level to be 9.74978 eV.

  • 21.
    Wang, Kai
    et al.
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM). Hebei Key Lab of Optic-electronic Information and Materials, College of Physics Science and Technology, Hebei University, Baoding, 071002, China.
    Bin Chen, Zhan
    College of Science, Hunan University of Technology, Zhuzhou, 412000, China.
    Zhang, Chun Yu
    Shanghai EBIT Lab, Key Laboratory of Nuclear Physics and Ion-beam Application, Institute of Modern Physics, Department of Nuclear Science and Technology, Fudan University, Shanghai, 200433, China.
    Si, Ran
    Shanghai EBIT Lab, Key Laboratory of Nuclear Physics and Ion-beam Application, Institute of Modern Physics, Department of Nuclear Science and Technology, Fudan University, Shanghai, 200433, China.
    Jönsson, Per
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Hartman, Henrik
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Gu, Ming Feng
    Space Science Laboratory, University of California, Berkeley, 94720, CA, United States.
    Chen, Chong Yang
    Shanghai EBIT Lab, Key Laboratory of Nuclear Physics and Ion-beam Application, Institute of Modern Physics, Department of Nuclear Science and Technology, Fudan University, Shanghai, 200433, China.
    Yan, Jun
    Institute of Applied Physics and Computational Mathematics, Beijing, 100088, China; Center for Applied Physics and Technology, Peking University, Beijing, 100871, China; Collaborative Innovation Center of IFSA (CICIFSA), Shanghai Jiao Tong University, Shanghai, 200240, China.
    Benchmarking Atomic Data for Astrophysics: Be-like Ions between B II and Ne VII2018Ingår i: Astrophysical Journal Supplement Series, ISSN 0067-0049, E-ISSN 1538-4365, Vol. 234, nr 2Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Large-scale self-consistent multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction calculations are reported for the n <= 6 levels in Be-like ions from B II to Ne VII. Effects from electron correlation are taken into account by means of large expansions in terms of a basis of configuration state functions, and a complete and accurate data set of excitation energies; lifetimes; wavelengths; electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole line strengths; transition rates; and oscillator strengths for these levels is provided for each ion. Comparisons are made with available experimental and theoretical results. The uncertainty of excitation energies is assessed to be 0.01% on average, which makes it possible to find and rule out misidentifications and aid new line identifications involving high-lying levels in astrophysical spectra. The complete data set is also useful for modeling and diagnosing astrophysical plasmas.

  • 22.
    Thorsbro, Brian
    et al.
    Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, SE-22100 Lund, Sweden.
    Ryde, Nils
    Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, SE-22100 Lund, Sweden.
    Schultheis, Mathias
    Observatoire de la Côte d'Azur, CNRS UMR 7293, BP4229, Laboratoire Lagrange, F-06304 Nice Cedex 4, France.
    Hartman, Henrik
    Malmö universitet, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM). Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, SE-22100 Lund, Sweden.
    Rich, Robert Martin
    Department of Physics and Astronomy, UCLA, 430 Portola Plaza, Box 951547, Los Angeles, CA 90095-1547, USA.
    Lomaeva, Maria
    Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, SE-22100 Lund, Sweden.
    Origlia, Livia
    INAF—Osservatorio Astronomico di Bologna, via Gobetti 93/3, I-40129 Bologna, Italy.
    Jönsson, Henrik
    Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, SE-22100 Lund, Sweden.
    Evidence against Anomalous Compositions for Giants in the Galactic Nuclear Star Cluster2018Ingår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 866, nr 1Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Very strong Sc I lines have recently been found in cool M giants in the Nuclear Star Cluster (NSC) in the Galactic center. Interpreting these as anomalously high scandium abundances in the Galactic center would imply a unique enhancement signature and chemical evolution history for NSCs, and a potential test for models of chemical enrichment in these objects. We present high resolution K-band spectra (NIRSPEC/Keck II) of cool M giants situated in the solar neighborhood and compare them with spectra of M giants in the NSC. We clearly identify strong Sc I lines in our solar neighborhood sample as well as in the NSC sample. The strong Sc I lines in M giants are therefore not unique to stars in the NSC and we argue that the strong lines are a property of the line formation process that currently escapes accurate theoretical modeling. We further conclude that for giant stars with effective temperatures below approximately 3800 K these Sc I lines should not be used for deriving the scandium abundances in any astrophysical environment until we better understand how these lines are formed. We also discuss the lines of vanadium, titanium, and yttrium identified in the spectra, which demonstrate a similar striking increase in strength below 3500 K effective temperature.

  • 23.
    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, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM). Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, 221 00 Lund, Sweden.
    Hartman, Henrik
    Malmö högskola, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM). Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, 221 00 Lund, Sweden.
    Jönsson, Per
    Malmö högskola, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (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 samples2017Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 598, artikel-id A100Artikel i tidskrift (Refereegranskat)
    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.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 24.
    Nicholls, Christine P
    et al.
    Institute for Astrophysics, University of Vienna, Türkenschanzstrasse 17, Vienna, 1180, Austria.
    Lebzelter, T
    Institute for Astrophysics, University of Vienna, Türkenschanzstrasse 17, Vienna, 1180, Austria.
    Smette, A
    European Southern Observatory, Casilla 19001, Alonso de Cordova, Vitacura, Santiago, 3107, Chile.
    Wolff, B
    European Southern Observatory, Karl-Schwarzschild-Str. 2, Garching bei München, 85748, Germany.
    Hartman, Henrik
    Malmö högskola, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM). Lund Observatory, Lund University, Box 43, Lund, 22100, Sweden.
    Käufl, H.-U.
    European Southern Observatory, Karl-Schwarzschild-Str. 2, Garching bei München, 85748, Germany.
    Przybilla, N.
    Institut für Astro-und Teilchenphysik, Universität Innsbruck, Technikerstr. 25/8, Innsbruck, 6020, Austria.
    Ramsay, S.
    European Southern Observatory, Karl-Schwarzschild-Str. 2, Garching bei München, 85748, Germany.
    Uttenthaler, S.
    Institute for Astrophysics, University of Vienna, Türkenschanzstrasse 17, Vienna, 1180, Austria.
    Wahlgren, G.
    CSRA/STScI, 3700 San Martin Drive, Baltimore, 21218, MD, United States.
    Bagnulo, G
    Armagh Observatory, College Hill, Armagh, BT619DG, United Kingdom.
    Hussain, G
    European Southern Observatory, Karl-Schwarzschild-Str. 2, Garching bei München, 85748, Germany; Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, UPS-OMP, Toulouse, 31400, France.
    Nieva, M.-F.
    Institut für Astro-und Teilchenphysik, Universität Innsbruck, Technikerstr. 25/8, Innsbruck, 6020, Austria.
    Seemann, U
    Institut für Astrophysik, Georg-August Universität Göttingen, Friedrich-Hund-Platz 1, Göttingen, 37077, Germany.
    Seifahrt, A.
    Department of Astronomy and Astrophysics, University of Chicago, 5640 S Ellis Avenue, Chicago, 60637, IL, United States.
    CRIRES-POP: a library of high resolution spectra in the near-infrared II. Data reduction and the spectrum of the K giant 10 Leonis2017Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 598, artikel-id A79Artikel i tidskrift (Refereegranskat)
    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.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 25.
    Pehlivan-Rhodin, Asli
    et al.
    Malmö högskola, Fakulteten för teknik och samhälle (TS). Lund Observatory, PO Box 43, 221 00 Lund, Sweden.
    Hartman, Henrik
    Malmö högskola, Fakulteten för teknik och samhälle (TS). Lund Observatory, PO Box 43, 221 00 Lund, Sweden.
    Nilsson, Hampus
    Lund Observatory, PO Box 43, 221 00 Lund, Sweden.
    Jönsson, Per
    Malmö högskola, Fakulteten för teknik och samhälle (TS).
    Experimental and theoretical oscillator strengths of Mg i for accurate abundance analysis2017Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 598, nr A102, artikel-id A102Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Context. With the aid of stellar abundance analysis, it is possible to study the galactic formation and evolution. Magnesium is an important element to trace the -element evolution in our Galaxy. For chemical abundance analysis, such as magnesium abundance, accurate and complete atomic data are essential. Inaccurate atomic data lead to uncertain abundances and prevent discrimination between di erent evolution models. Aims.We study the spectrum of neutral magnesium from laboratory measurements and theoretical calculations. Our aim is to improve the oscillator strengths ( f -values) of Mgi lines and to create a complete set of accurate atomic data, particularly for the near-IR region. Methods. We derived oscillator strengths by combining the experimental branching fractions with radiative lifetimes reported in the literature and computed in this work. A hollow cathode discharge lamp was used to produce free atoms in the plasma and a Fourier transform spectrometer recorded the intensity-calibrated high-resolution spectra. In addition, we performed theoretical calculations using the multiconfiguration Hartree-Fock program ATSP2K. Results. This project provides a set of experimental and theoretical oscillator strengths. We derived 34 experimental oscillator strengths. Except from the Mgi optical triplet lines (3p 3Po0;1;2 - 4s 3S1), these oscillator strengths are measured for the first time. The theoretical oscillator strengths are in very good agreement with the experimental data and complement the missing transitions of the experimental data up to n = 7 from even and odd parity terms. We present an evaluated set of oscillator strengths, gf, with uncertainties as small as 5%. The new values of the Mgi optical triplet line (3p 3Po0 ;1;2 - 4s 3S1) oscillator strength values are 0.08 dex larger than the previous measurements.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 26.
    Pehlivan Rhodin, Asli
    et al.
    Malmö högskola, Fakulteten för teknik och samhälle (TS). Lund Observatory, Lund University, PO Box 43, SE-221 00 Lund, Sweden.
    Belmonte, Teruca
    Physics Department, Blackett Laboratory, Imperial College London, London SW7 2BZ, UK.
    Engström, Lars
    Department of Physics, Lund Institute of Technology, PO Box 118, SE-221 00 Lund, Sweden.
    Lundberg, Hans
    Department of Physics, Lund Institute of Technology, PO Box 118, SE-221 00 Lund, Sweden.
    Nilsson, Hampus
    Lund Observatory, Lund University, PO Box 43, SE-221 00 Lund, Sweden.
    Hartman, Henrik
    Malmö högskola, Fakulteten för teknik och samhälle (TS). Lund Observatory, Lund University, PO Box 43, SE-221 00 Lund, Sweden.
    Pickering, Juliet
    Physics Department, Blackett Laboratory, Imperial College London, London SW7 2BZ, UK.
    Clear, Christian
    Physics Department, Blackett Laboratory, Imperial College London, London SW7 2BZ, UK.
    Quinet, Pascal
    Physique Atomique et Astrophysique, Université de Mons–UMONS, 20 Place du Parc, B-7000 Mons, Belgium; IPNAS, Université de Liège, B15 Sart Tilman, B-4000 Liège, Belgium.
    Fivet, Vanessa
    Physique Atomique et Astrophysique, Université de Mons–UMONS, 20 Place du Parc, B-7000 Mons, Belgium.
    Palmeri, Patrick
    Physique Atomique et Astrophysique, Université de Mons–UMONS, 20 Place du Parc, B-7000 Mons, Belgium.
    Lifetime measurements and oscillator strengths insingly ionized scandium and the solar abundance of scandium2017Ingår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 472, nr 3, s. 3337-3353Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The lifetimes of 17 even-parity levels (3d5s, 3d4d, 3d6s, and 4p$^2$) in the region 57743-77837 cm$^{-1}$ of singly ionised scandium (\ion{Sc}{ii}) were measured by two-step time-resolved laser induced fluorescence spectroscopy. Oscillator strengths of 57 lines from these highly excited upper levels were derived using a hollow cathode discharge lamp and a Fourier transform spectrometer. In addition, Hartree--Fock calculations where both the main relativistic and core-polarisation effects were taken into account were carried out for both low- and high-excitation levels. There is a good agreement for most of the lines between our calculated branching fractions and the measurements of Lawler and Dakin (1989) in the region 9000-45000 cm$^{-1}$ for low excitation levels and with our measurements for high excitation levels in the region 23500-63100 cm$^{-1}$. This, in turn, allowed us to combine the calculated branching fractions with the available experimental lifetimes to determine semi-empirical oscillator strengths for a set of 380 E1 transitions in \ion{Sc}{ii}. These oscillator strengths include the weak lines that were used previously to derive the solar abundance of scandium. The solar abundance of scandium is now estimated to $\log~\epsilon_\odot = 3.04\pm0.13$ using these semi-empirical oscillator strengths to shift the values determined by Scott et al. (2015). The new estimated abundance value is in agreement with the meteoritic value ($\log~\epsilon_{\text{met}}=3.05\pm0.02$) of Lodders et al. (2009).

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 27.
    Palmeri, Patrick
    et al.
    IPNAS, Université de Liège, Campus du Sart-Tilman, B-4000 Liège, Belgium.
    Quinet, Pascal
    IPNAS, Université de Liège, Campus du Sart-Tilman, B-4000 Liège, Belgium; IPNAS, Université de Liège, Campus du Sart-Tilman, B-4000 Liège, Belgium.
    Lundberg, Hans
    Department of Physics, Lund University, Box 118, SE-221 00 Lund, Sweden.
    Engström, Lars
    Department of Physics, Lund University, Box 118, SE-221 00 Lund, Sweden.
    Nilsson, Hampus
    Lund Observatory, Lund University, Box 43, SE-221 00 Lund, Sweden.
    Hartman, Henrik
    Malmö högskola, Fakulteten för teknik och samhälle (TS). Lund Observatory, Lund University, Box 43, SE-221 00 Lund, Sweden.
    Lifetime measurements using two-step laser excitation for high-lying even-parity levels and improved theoretical oscillator strengths in Y II2017Ingår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 471, nr 1, s. 532-540Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report new time-resolved laser-induced fluorescence lifetime measurements for 22 highly excited even-parity levels in singly ionized yttrium (Y II). To populate these levels belonging to the configurations 4d6s, 5s6s 4d5d, 5p2, 4d7s and 4d6d, a two-step laser excitation technique was used. Our previous pseudo-relativistic Hartree–Fock model (Bi´emont et al. 2011) was improved by extending the configuration interaction up to n = 10 to reproduce the new experimental lifetimes. A set of semi-empirical oscillator strengths extended to transitions falling in the spectral range λλ194–3995 nm, depopulating these 22 even-parity levels in Y II, is presented and compared to the values found in the Kurucz’s data base (Kurucz 2011).

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 28.
    Jönsson, Per
    et al.
    Malmö högskola, Fakulteten för teknik och samhälle (TS).
    Gaigalas, Gediminas
    Institute of Theoretical Physics and Astronomy, Vilnius University, Sauletekio av. 3, Vilnius, LT-10222, Lithuania.
    Rynkun, Pavel
    Institute of Theoretical Physics and Astronomy, Vilnius University, Sauletekio av. 3, Vilnius, LT-10222, Lithuania.
    Radziute, Laima
    Institute of Theoretical Physics and Astronomy, Vilnius University, Sauletekio av. 3, Vilnius, LT-10222, Lithuania.
    Ekman, Jörgen
    Malmö högskola, Fakulteten för teknik och samhälle (TS).
    Gustafsson, Stefan
    Malmö högskola, Fakulteten för teknik och samhälle (TS).
    Hartman, Henrik
    Malmö högskola, Fakulteten för teknik och samhälle (TS).
    Wang, Kai
    Malmö högskola, Fakulteten för teknik och samhälle (TS).
    Godefroid, Michel
    Chimie Quantique et Photophysique, Université libre de Bruxelles, Brussels, B-1050, Belgium.
    Fischer, Charlotte Froese
    Department of Computer Science, University of British Columbia, Vancouver, V6T 1Z4, BC, Canada.
    Grant, Ian
    Mathematical Institute, University of Oxford, Woodstock Road, Oxford, OX2 6GG, United Kingdom; Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA, United Kingdom.
    Brage, Tomas
    Division of Mathematical Physics, Department of Physics, Lund University, Lund, 221-00, Sweden.
    Del Zanna, Giulio
    Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA, United Kingdom.
    Multiconfiguration Dirac-Hartree-Fock Calculations with Spectroscopic Accuracy: Applications to Astrophysics2017Ingår i: Atoms, E-ISSN 2218-2004, Vol. 5, nr 2, artikel-id 16Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Atomic data, such as wavelengths, spectroscopic labels, broadening parameters and transition rates, are necessary for many applications, especially in plasma diagnostics, and for interpreting the spectra of distant astrophysical objects. The experiment with its limited resources is unlikely to ever be able to provide a complete dataset on any atomic system. Instead, the bulk of the data must be calculated. Based on fundamental principles and well-justified approximations, theoretical atomic physics derives and implements algorithms and computational procedures that yield the desired data. We review progress and recent developments in fully-relativistic multiconfiguration Dirac-Hartree-Fock methods and show how large-scale calculations can give transition energies of spectroscopic accuracy, i.e., with an accuracy comparable to the one obtained from observations, as well as transition rates with estimated uncertainties of a few percent for a broad range of ions. Finally, we discuss further developments and challenges.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 29.
    Hartman, Henrik
    et al.
    Malmö högskola, Fakulteten för teknik och samhälle (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 calculations2017Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 600, artikel-id A108Artikel i tidskrift (Refereegranskat)
    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.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 30.
    Quinet, Pascal
    et al.
    Physique Atomique et Astrophysique, Université de Mons, B-7000 Mons, Belgium; IPNAS, Université de Liège, Sart Tilman, B-4000 Liège, Belgium.
    Fivet, Vanessa
    Physique Atomique et Astrophysique, Université de Mons, B-7000 Mons, Belgium.
    Palmeri, Patrick
    Physique Atomique et Astrophysique, Université de Mons, B-7000 Mons, Belgium.
    Engström, Lars
    Department of Physics, Lund University, Box 118, SE-221 00 Lund, Sweden.
    Hartman, Henrik
    Malmö högskola, Fakulteten för teknik och samhälle (TS). Lund Observatory, Lund University, Box 43, SE-221 00 Lund, Sweden.
    Lundberg, Hans
    Department of Physics, Lund University, Box 118, SE-221 00 Lund, Sweden.
    Nilsson, Hampus
    Lund Observatory, Lund University, Box 43, SE-221 00 Lund, Sweden.
    Experimental radiative lifetimes for highly excited states and calculated oscillator strengths for lines of astrophysical interest in singly ionized cobalt (Co II)2016Ingår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 462, nr 4, s. 3912-3917Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work reports new experimental radiative lifetimes and calculated oscillator strengths for transitions of astrophysical interest in singly ionized cobalt. More pre- cisely, nineteen radiative lifetimes in Co+ have been measured with the time-resolved laser-induced fluorescence technique using one- and two-step excitations. Out of these, seven belonging to the high lying 3d7(4F)4d configuration in the energy range 90697 - 93738 cm 1 are new, and the other twelve from the 3d7(4F)4p configuration with energies between 45972 and 49328 cm 1 are compared with previous measurements. In addition, a relativistic Hartree-Fock model including core-polarization e ects has been employed to compute transition rates. Supported by the good agreement between theory and experiment for the lifetimes, new reliable transition probabilities and os- cillator strengths have been deduced for 5080 Co ii transitions in the spectral range 114- 8744 nm.

  • 31.
    Holmes, Charlotte
    et al.
    Blackett Laboratory, Dept. Physics, Imperial College London, London SW7 2AZ, UK.
    Pickering, Juliet
    Blackett Laboratory, Dept. Physics, Imperial College London, London SW7 2AZ, UK.
    Ruffoni, Matthew
    Blackett Laboratory, Dept. Physics, Imperial College London, London SW7 2AZ, UK.
    Blackwell-Whitehead, Richard
    Blackett Laboratory, Dept. Physics, Imperial College London, London SW7 2AZ, UK.
    Nilsson, Hampus
    Blackett Laboratory, Dept. Physics, Imperial College London, London SW7 2AZ, UK.
    Engström, Lars
    Blackett Laboratory, Dept. Physics, Imperial College London, London SW7 2AZ, UK.
    Hartman, Henrik
    Blackett Laboratory, Dept. Physics, Imperial College London, London SW7 2AZ, UK.
    Lundberg, Hans
    Blackett Laboratory, Dept. Physics, Imperial College London, London SW7 2AZ, UK.
    Belmonte, M
    Blackett Laboratory, Dept. Physics, Imperial College London, London SW7 2AZ, UK.
    Experimentally Measured Radiative Lifetimes and Oscillator Strengths in Neutral Vanadium2016Ingår i: Astrophysical Journal Supplement Series, ISSN 0067-0049, E-ISSN 1538-4365, Vol. 224, nr 2, artikel-id 35Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report a new study of the V i atom using a combination of time-resolved laser-induced fluorescence and Fourier transform spectroscopy that contains newly measured radiative lifetimes for 25 levels between 24,648 cm-1 and 37,518 cm-1 and oscillator strengths for 208 lines between 3040 and 20000 Å from 39 upper energy levels. Thirteen of these oscillator strengths have not been reported previously. This work was conducted independently of the recent studies of neutral vanadium lifetimes and oscillator strengths carried out by Den Hartog et al. and Lawler et al., and thus serves as a means to verify those measurements. Where our data overlap with their data, we generally find extremely good agreement in both level lifetimes and oscillator strengths. However, we also find evidence that Lawler et al. have systematically underestimated oscillator strengths for lines in the region of 9000 ± 100 Å. We suggest a correction of 0.18 ± 0.03 dex for these values to bring them into agreement with our results and those of Whaling et al. We also report new measurements of hyperfine structure splitting factors for three odd levels of V i lying between 24,700 and 28,400 cm-1.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 32.
    Lundberg, Hans
    et al.
    Department of Physics, Lund University, PO Box 118, SE-221 00 Lund, Sweden.
    Hartman, Henrik
    Malmö högskola, Fakulteten för teknik och samhälle (TS). Department of Astronomy and Theoretical Physics, Lund University, PO Box 43, SE-221 00 Lund, Sweden.
    Engström, Lars
    Department of Physics, Lund University, PO Box 118, SE-221 00 Lund, Sweden.
    Nilsson, Hampus
    Department of Physics, Lund University, PO Box 118, SE-221 00 Lund, Sweden.
    Persson, Anders
    Department of Physics, Lund University, PO Box 118, SE-221 00 Lund, Sweden.
    Palmeri, Patrick
    Physique Atomique et Astrophysique, Université de Mons, B-7000 Mons, Belgium.
    Quinet, P.
    Physique Atomique et Astrophysique, Université de Mons, B-7000 Mons, Belgium; IPNAS, Université de Liège, B-4000 Liège, Belgium.
    Fivet, Vanessa
    Physique Atomique et Astrophysique, Université de Mons, B-7000 Mons, Belgium.
    Malcheva, G
    Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee, BG-1784 Sofia, Bulgaria.
    Blagoev, Kiril
    Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee, BG-1784 Sofia, Bulgaria.
    Oscillator strengths for high-excitation Ti II from laboratory measurements and calculations2016Ingår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 460, nr 1, s. 356-362Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work reports new experimental radiative lifetimes of six 3d2(3F)5s levels in singly ionized titanium, with an energy around 63 000 cm−1 and four 3d2(3F)4p odd parity levels where we confirm previous investigations. Combining the new 5s lifetimes with branching fractions measured previously by Pickering et al., we report 57 experimental log gf values for transitions from the 5s levels. The lifetime measurements are performed using time-resolved laser-induced fluorescence on ions produced by laser ablation. One- and two-step photon excitation is employed to reach the 4p and 5s levels, respectively. Theoretical calculations of the radiative lifetimes of the measured levels as well as of oscillator strengths for 3336 transitions from these levels are reported. The calculations are carried out by a pseudo relativistic Hartree–Fock method taking into account core-polarization effects. The theoretical results are in a good agreement with the experiments and are needed for accurate abundance determinations in astronomical objects.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 33. Thomas, R.D.
    et al.
    Schmidt, H.T.
    Gatchell, M
    Rosén, S
    Reinhed, P
    Löfgren, P
    Brännholm, L
    Blom, M
    Björkhage, M
    Bäckström, E
    Alexander, J.D.
    Leontein, S
    Hanstorp, D
    Zettergren, H
    Kaminska, M
    Nascimento, R.D.
    Liljeby, L
    Källberg, Asli
    Simonsson, A
    Hellberg, F
    Mannervik, S
    Larsson, M
    Geppert, W.D.
    Rensfelt, K.G.
    Paal, A
    Masuda, M
    Halldén, P
    Andler, G
    Stockett, M
    Chen, T
    Källersjö, G
    Weimer, J.D.
    Hansen, K
    Hartman, Henrik
    Malmö högskola, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Cederquist, H
    DESIREE: Physics with cold stored ion beams2015Ingår i: DR2013: Ninth International Conference on Dissociative Recombination: Theory, Experiment, and Applications, EDP Sciences, 2015, artikel-id 01004Konferensbidrag (Refereegranskat)
    Abstract [en]

    Here we will briefly describe the commissioning of the Double ElectroStatic Ion Ring ExpEriment (DESIREE) facility at Stockholm University, Sweden. This device uses purely electrostatic focussing and deflection elements and allows ion beams of opposite charge to be confined under extreme high vacuum and cryogenic conditions in separate “rings” and then merged over a common straight section. This apparatus allows for studies of interactions between cations and anions at very low and well-defined centre-of-mass energies (down to a few meV) and at very low internal temperatures (down to a few K).

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 34.
    Pehlivan, Asli
    et al.
    Malmö högskola, Fakulteten för teknik och samhälle (TS). Lund Observatory, Box 43, 221 00 Lund, Sweden.
    Nilsson, Hampus
    Lund Observatory, Box 43, 221 00 Lund, Sweden.
    Hartman, Henrik
    Malmö högskola, Fakulteten för teknik och samhälle (TS). Lund Observatory, Box 43, 221 00 Lund, Sweden.
    Laboratory oscillator strengths of Sc i in the near-infrared region for astrophysical applications2015Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 582, nr A98, artikel-id A98Artikel i tidskrift (Refereegranskat)
    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

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 35. Macheva, G
    et al.
    Engström, L
    Lundberg, H
    Nilsson, H
    Hartman, Henrik
    Malmö högskola, Fakulteten för teknik och samhälle (TS).
    Blagoev, K
    Palmeri, P
    Quinet, P
    Radiative lifetimes and transition probabilities in Rh I2015Ingår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 450, nr 1, s. 223-228Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Radiative lifetimes of 17 high-lying excited states in Rh I aremeasured using the time-resolved laser-induced fluorescence method. Out of these lifetimes, 13 are new and the remaining four confirm previous measurements. Furthermore, we report the first theoretical investigation of Rh I, where the radiative decay properties of all experimentally known levels below 47 000 cm−1 are calculated using a pseudo-relativistic Hartree–Fock method including core polarization effects. The theoretical calculations are found to be in very good agreement with the experimental results. A large set of new transition probabilities is presented for lines of astrophysical interest in the spectral range 2200–10 000 Å.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 36.
    Hartman, Henrik
    et al.
    Malmö högskola, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (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 ii2015Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 584, nr A24, artikel-id A24Artikel i tidskrift (Refereegranskat)
    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.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 37.
    Jönsson, Per
    et al.
    Malmö högskola, Teknik och samhälle (TS).
    Ekman, Jörgen
    Malmö högskola, Teknik och samhälle (TS).
    Froese Fischer, Charlotte
    Gaigalas, Gediminas
    Godefroid, Michel
    Hartman, Henrik
    Malmö högskola, Teknik och samhälle (TS).
    Rynkun, Pavel
    Atomic Structure Calculations with Spectroscopic Accuracy: Implications for Laboratory Work2014Ingår i: Ninth International Conference on Atomic and Molecular Data and Their Applications: book of abstracts, 2014, s. 112-112Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The observation of atomic spectra constitutes an important tool for diagnostics of astrophysical plasmas, and there is a boom of activity involving several new and planned multibillion-dollar telescopes. However, to correctly interpret observed spectra, the atomic lines must be known and identified from laboratory work. Laboratory work is hard and time-consuming, and present efforts do not in any way match the needs for data, partly due to lack of funding [1] and partly due to experimental limitations. One goal of atomic structure calculations is to provide energy differences with ”spectroscopic accuracy” to aid laboratory work. Using highly accurate calculated energy differences it should be possible to directly validate or rule out experimental energy level and line identifications. New and efficient methods for solving the Dirac-equation for many electron systems, together with today’s fast computers, indeed make it possible to perform calculations with spectroscopic accuracy for ions of medium complexity. We give a number of examples of calculations based on the relativistic configuration interaction (RCI) method in B-, C-, N-, O-, and Ne-like systems, where energies levels far up in the spectrum have been predicted with uncertainties of 0.05 % or less [2,3,4]. Depending on the spectral range, these uncertainties are in many cases close to what can be experimentally obtained. The above mentioned calculations reveal that many experimental energy levels given in the literature and in data bases are wrong and based on misidentifications. We finally show how the accuracy of atomic structure calculations can be further improved, and results extended to more complex systems, by using the novel partitioned configuration function interaction (PCFI) method [5]. Some practical consequences of the recent advances in computational methodology for laboratory work are discussed.

  • 38.
    Ekman, Jörgen
    et al.
    Malmö högskola, Teknik och samhälle (TS).
    Jönsson, Per
    Malmö högskola, Teknik och samhälle (TS).
    Gustafsson, Stefan
    Malmö högskola, Teknik och samhälle (TS).
    Hartman, Henrik
    Malmö högskola, Teknik och samhälle (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 XXV2014Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 564, artikel-id A24Artikel i tidskrift (Refereegranskat)
    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.

  • 39. Gatchell, M
    et al.
    Schmeidt, H.T.
    Thomas, R.D.
    Rosen, S
    Reinhed, P
    Löfgren, P
    Brännholm, L
    Blom, M
    Björkhage, M
    Bäckström, E
    Alexander, J.D.
    Leontein, S
    Hanstorp, D.
    Zettergren, H
    Liljeby, L
    Källberg, A
    Simonsson, A
    Hellberg, F
    Mannervik, S
    Larsson, M
    Geppert, W.D.
    Rensfelt, K.G.
    Danared, H
    Paal, A
    Masuda, M
    Hallden, P
    Andler, G
    Stockett, M
    Chen, T
    Källersjö, G
    Weimer, J
    Hansen, K
    Hartman, Henrik
    Malmö högskola, Teknik och samhälle (TS).
    Cederquist, H
    Commissioning of the DESIREE storage rings: a new facility for cold ion-ion collisions2014Ingår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 488, nr 1, artikel-id 012040Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on the ongoing commissioning of the Double ElectroStatic Ion Ring ExpEriment, DESIREE, at Stockholm University. Beams of atomic carbon anions (C‑) and smaller carbon anion molecules (C‑2, C‑3, C‑4 etc.) have been produced in a sputter ion source, accelerated to 10 keV or 20 keV, and stored successfully in the two electrostatic rings. The rings are enclosed in a common vacuum chamber cooled to below 13 Kelvin. The DESIREE facility allows for studies of internally relaxed single isolated atomic, molecular and cluster ions and for collision experiments between cat- and anions down to very low center-of-mass collision energies (meV scale). The total thermal load of the vacuum chamber at this temperature is measured to be 32 W. The decay rates of stored ion beams have two components: a non-exponential component caused by the space charge of the beam itself which dominates at early times and an exponential term from the neutralization of the beam in collisions with residual gas at later times. The residual gas limited storage lifetime of carbon anions in the symmetric ring is over seven minutes while the 1/e lifetime in the asymmetric ring is measured to be about 30 seconds. Although we aim to improve the storage in the second ring, the number of stored ions are now sufficient for many merged beams experiments with positive and negative ions requiring milliseconds to seconds ion storage.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 40.
    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, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (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 ii2014Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 570, artikel-id A34Artikel i tidskrift (Refereegranskat)
    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.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 41.
    Ekman, Jörgen
    et al.
    Malmö högskola, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Godefroid, Michel R.
    Univ Libre Bruxelles, Chim Quant & Photophys, B-1050 Brussels, Belgium..
    Hartman, Henrik
    Malmö högskola, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM).
    Validation and Implementation of Uncertainty Estimates of Calculated Transition Rates2014Ingår i: Atoms, E-ISSN 2218-2004, Vol. 2, nr 2, s. 215-224Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Uncertainties of calculated transition rates in LS-allowed electric dipole transitions in boron-like O IV and carbon-like Fe XXI are estimated using an approach in which differences in line strengths calculated in length and velocity gauges are utilized. Estimated uncertainties are compared and validated against several high-quality theoretical data sets in O IV, and implemented in large scale calculations in Fe XXI.

    Ladda ner fulltext (pdf)
    fulltext
  • 42.
    Ekman, Jörgen
    et al.
    Malmö högskola, Teknik och samhälle (TS).
    Grumer, Jon
    Hartman, Henrik
    Malmö högskola, Teknik och samhälle (TS).
    Jönsson, Per
    Malmö högskola, Teknik och samhälle (TS).
    A spectral study of Te V from MCDHF calculations2013Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 46, nr 9, artikel-id 095001Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    State-of-the-art multiconfiguration Dirac-Hartree-Fock calculations for Te V have been performed and energies, LS-compositions, radiative lifetimes and Landé gJ-factors for 51 odd and even parity states are presented. In addition, predictions on transition rates and oscillator strengths for a multitude of transitions between these states are reported for the first time. To describe the atomic system accurately, by means of configuration interaction, valence and core-valence electron correlation effects were taken into account. Calculated energies and lifetimes of excited states agree very well with experimental data.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 43.
    Karlsson, Lennart
    et al.
    Malmö högskola, Teknik och samhälle (TS).
    Ekman, Jörgen
    Malmö högskola, Teknik och samhälle (TS).
    Gustafsson, Stefan
    Malmö högskola, Teknik och samhälle (TS).
    du Rietz, Rickard
    Malmö högskola, Teknik och samhälle (TS).
    Hartman, Henrik
    Malmö högskola, Teknik och samhälle (TS).
    Jönsson, Per
    Malmö högskola, Teknik och samhälle (TS).
    Accurate calculations of atomic properties for boron- and carbon-like ions of astrophysical interest2013Konferensbidrag (Övrigt vetenskapligt)
    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 44.
    Jönsson, Per
    et al.
    Malmö högskola, Teknik och samhälle (TS).
    Ekman, Jörgen
    Malmö högskola, Teknik och samhälle (TS).
    Gustafsson, Stefan
    Malmö högskola, Teknik och samhälle (TS).
    Hartman, Henrik
    Malmö högskola, Teknik och samhälle (TS).
    Karlsson, Lennart
    Malmö högskola, Teknik och samhälle (TS).
    du Rietz, Rickard
    Malmö högskola, Teknik och samhälle (TS).
    Gaigalas, Gediminas
    Godefroid, Michel
    Froese Fischer, Charlotte
    Energy levels and transition rates for the boron isoelectronic sequence: Si X, Ti XVIII – Cu XXV2013Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 559, artikel-id A100Artikel i tidskrift (Refereegranskat)
    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.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 45.
    Bäckström, Erik
    et al.
    Department of Physics, Stockholm University.
    Nilsson, H.
    Lund Observatory.
    Engström, L.
    Department of Physics, Lund University.
    Hartman, Henrik
    Malmö högskola, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM). Lund Observatory.
    Mannervik, S.
    Department of Physics, Stockholm University.
    Experimentally determined oscillator strengths in Rh II2013Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 46, nr 20, artikel-id 205001Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents new experimentally determined branching fractions and oscillator strengths (log gf) for lines originating from 17 levels belonging to 5 terms of the first excited odd configuration 4d7(4D)5p in Rh II. The intensity calibrated spectra of Rh II have been recorded with a Fourier transform spectrometer between 25000 and 45000 cm−1 (2200–4000 Å). In this region, 49 lines have been identified and measured. By combining the branching fractions obtained from the spectra with previously measured lifetimes, log gf values are reported. The new results are compared with previous theoretical work.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 46. Schmidt, H.T.
    et al.
    Thomas, R.D.
    Gatchell, M.
    Rosen, S
    Reinhed, P.
    Löfgren, P
    Brännholm, L
    Blom, M
    Björkhage, M
    Bäckström, E
    Alexander, J.D.
    Leontein, S
    Hanstorp, D
    Zettergren, H
    Liljeby, L
    Källberg, A
    Simonsson, A
    Hellberg, F
    Mannervik, S
    Larsson, M
    Geppert, W D
    Rensfelt, K G
    Danered, H
    Paál, A
    Masuda, M
    Halldén, P
    Andler, G
    Stockett, M H
    Chen, T
    Källersjö, G
    Weimer, J
    Hansen, K
    Hartman, Henrik
    Malmö högskola, Teknik och samhälle (TS).
    Cederquist, H
    First storage of ion beams in the Double Electrostatic Ion-Ring Experiment: DESIREE2013Ingår i: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 84, nr 5, artikel-id 055115Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on the first storage of ion beams in the Double ElectroStatic Ion Ring ExpEriment, DESIREE, at Stockholm University. We have produced beams of atomic carbon anions and small carbon anion molecules (Cn-, n = 1, 2, 3, 4) in a sputter ion source. The ion beams were accelerated to 10 keV kinetic energy and stored in an electrostatic ion storage ring enclosed in a vacuum chamber at 13 K. For 10 keV C2- molecular anions we measure the residual-gas limited beam storage lifetime to be 448 s +/- 18 s with two independent detector systems. Using the measured storage lifetimes we estimate that the residual gas pressure is in the 10-14 mbar range. When high current ion beams are injected, the number of stored particles does not follow a single exponential decay law as would be expected for stored particles lost solely due to electron detachment in collision with the residual-gas. Instead, we observe a faster initial decay rate, which we ascribe to the effect of the space charge of the ion beam on the storage capacity.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 47.
    Hartman, Henrik
    Malmö högskola, Teknik och samhälle (TS).
    Fluorescence in astrophysical plasmas2013Ingår i: New Trends in Atomic and Molecular Physics: Advanced Technological Applications / [ed] Man Mohan, Springer, 2013, s. 189-200Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    Following the initial detection by Bowen in 1934 of the strong O III lines being due to accidental resonance with strong He II radiation, many strong spectral emission lines are explained as produced by fluorescence. Many of these are Fe II lines pumped by H Lyα, as a consequence of strong radiation from hydrogen and a favorable energy level structure for Fe II. The lines are observed in many types of objects with low density plasma components. The Weigelt condensations in the vicinity of the massive star Eta Carinae is one location where these lines are observed and can be studied in detail, as well as been used for diagnostics. These gas condensations do not only show a spectrum indicating a nonequilibrium excitation but also non-equilibrium ionization, where the strong hydrogen radiation plays a key role. Early studies identified certain strong lines being the result of Resonance Enhanced Two-Photon Ionization (RETPI). Further investigations suggest that RETPI can be the responsible mechanism for the ionization structure of gas condensation. We will review the resonance processes, with emphasis on the Eta Carinae spectrum. Large spectral, spatial and temporal coverage is available for this fascinating object, allowing for detailed analysis.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 48.
    Galcheva, M.
    et al.
    Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee, BG-1784 Sofia, Bulgaria.
    Engström, Lars
    Department of Physics, Lund University, Box 118, SE-221 00 Lund, Sweden.
    Lundberg, H.
    Department of Physics, Lund University, Box 118, SE-221 00 Lund, Sweden.
    Nilsson, H.
    Lund Observatory, Lund University, Box 43, SE-22100 Lund, Sweden.
    Hartman, Henrik
    Malmö högskola, Fakulteten för teknik och samhälle (TS), Institutionen för materialvetenskap och tillämpad matematik (MTM). Lund Observatory, Lund University, Box 43, SE-22100 Lund, Sweden.
    Blagoev, K.
    Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee, BG-1784 Sofia, Bulgaria.
    Lifetime measurements of even and odd states in neutral terbium (Tb I)2013Ingår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 88, nr 4, artikel-id 045304Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Radiative lifetimes of 7 odd and 11 even parity states of Tb I (Z = 65) have been measured by the time resolved laser induced fluorescence method (TR-LIF). Experimental data for 9 out of the 18 states are obtained for the first time. The radiative lifetimes presented in this study are in good agreement with previous TR-LIF experimental results but systematically shorter than those obtained by the delayed coincidence technique.

  • 49.
    Ekman, Jörgen
    et al.
    Malmö högskola, Teknik och samhälle (TS).
    Jönsson, Per
    Malmö högskola, Teknik och samhälle (TS).
    Gustafsson, Stefan
    Malmö högskola, Teknik och samhälle (TS).
    Hartman, Henrik
    Malmö högskola, Teknik och samhälle (TS).
    du Rietz, Rickard
    Malmö högskola, Teknik och samhälle (TS).
    Gaigalas, Gediminas
    Godefroid, Michel
    Froese Fischer, Charlotte
    Massive Calculations of Atomic Properties with High Accuracy for Boron-like Iron and other Ions of Astrophysical Interest2013Ingår i: Book of abstracts;Abstract ID 17748, Institute of Modern Physics, Chinese Academy of Sciences , 2013Konferensbidrag (Övrigt vetenskapligt)
    Ladda ner fulltext (pdf)
    FULLTEXT01
    Ladda ner fulltext (pdf)
    FULLTEXT02
  • 50.
    Pallé, P L
    et al.
    Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain; Department de Astrofísica, Universidad de la Laguna, E-38206 La Laguna, Tenerife, Spain.
    Grundahl, F
    Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Denmark.
    Hage, A Triviño
    Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain; Department de Astrofísica, Universidad de la Laguna, E-38206 La Laguna, Tenerife, Spain.
    Christensen-Dalsgaard, J
    Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Denmark.
    Frandsen, S
    Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Denmark.
    García, R A
    Laboratoire AIM, CEA/DSM-CNRS-Université Paris Diderot, CEA, F-91191, Gif-sur-Yvette, France.
    Uytterhoeven, K
    Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain; Department de Astrofísica, Universidad de la Laguna, E-38206 La Laguna, Tenerife, Spain.
    Andersen, M F
    Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Denmark.
    Rasmussen, P K
    Niels Bohr Institute, University of Copenhagen, Kbenhavn Ø, 2100, Juliane Maries Vej 30, Denmark.
    Sørensen, A N
    Niels Bohr Institute, University of Copenhagen, Kbenhavn Ø, 2100, Juliane Maries Vej 30, Denmark.
    Kjeldsen, H
    Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Denmark.
    Spano, P
    INAF, Osservatorio Astronomico di Brera, Italy.
    Nilsson, H
    Lund Observatory, Lund University, SE-221 00 Lund, Box 43, Sweden.
    Hartman, H
    Lund Observatory, Lund University, SE-221 00 Lund, Box 43, Sweden.
    Jørgensen, U G
    Niels Bohr Institute, University of Copenhagen, Kbenhavn Ø, 2100, Juliane Maries Vej 30, Denmark; Centre for Star and Planet Formation, Natural History Museum of Denmark, University of Copenhagen, København K, 1350, Øster Voldgade 5-7, Denmark.
    Skottfelt, J
    Niels Bohr Institute, University of Copenhagen, Kbenhavn Ø, 2100, Juliane Maries Vej 30, Denmark; Centre for Star and Planet Formation, Natural History Museum of Denmark, University of Copenhagen, København K, 1350, Øster Voldgade 5-7, Denmark.
    Harpsøe, K
    Niels Bohr Institute, University of Copenhagen, Kbenhavn Ø, 2100, Juliane Maries Vej 30, Denmark; Centre for Star and Planet Formation, Natural History Museum of Denmark, University of Copenhagen, København K, 1350, Øster Voldgade 5-7, Denmark.
    Andersen, M I
    Niels Bohr Institute, University of Copenhagen, Kbenhavn Ø, 2100, Juliane Maries Vej 30, Denmark.
    Observations of the radial velocity of the Sun as measured with the novel SONG spectrograph: results from a 1-week campaign2013Ingår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 440, s. 012051-012051Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Deployment of the prototype node of the SONG project took place in April 2012 at Observatorio del Teide (Canary Islands). Its key instrument (echelle spectrograph) was installed and operational a few weeks later while its 1 m feeding telescope suffered a considerable delay to meet the required specifications. Using a fibre-feed, solar light could be fed to the spectrograph and we carried out a 1-week observing campaign in June 2012 to evaluate its performance for measuring precision radial velocities. In this work we present the first results of this campaign by comparing the sensitivity of the SONG spectrograph with other helioseismology reference instruments (Mark-I and GOLF) when simultaneous data are considered.

12 1 - 50 av 67
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf