Adding the s-Process Element Cerium to the APOGEE Survey: Identification and Characterization of Ce II Lines in the H-band Spectral WindowShow others and affiliations
2017 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 844, no 2, article id 145Article in journal (Refereed) Published
Abstract [en]
Nine Ce II lines have been identified and characterized within the spectral window observed by the Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey (between lambda 1.51 and 1.69 mu m). At solar metallicities, cerium is an element that is produced predominantly as a result of the slow capture of neutrons (the s-process) during asymptotic giant branch stellar evolution. The Ce II lines were identified using a combination of a high-resolution (R = lambda/delta lambda = 100,000) Fourier Transform Spectrometer (FTS) spectrum of a Boo and an APOGEE spectrum (R. =. 22,400) of a metal-poor, but s-process enriched, red giant (2M16011638-1201525). Laboratory oscillator strengths are not available for these lines. Astrophysical gf-values were derived using alpha Boo as a standard star, with the absolute cerium abundance in alpha Boo set by using optical Ce II lines that have precise published laboratory gf-values. The near-infrared Ce II lines identified here are also analyzed, as consistency checks, in a small number of bright red giants using archival FTS spectra, as well as a small sample of APOGEE red giants, including two members of the open cluster NGC 6819, two field stars, and seven metal-poor N-and Al-rich stars. The conclusion is that this set of Ce II lines can be detected and analyzed in a large fraction of the APOGEE red giant sample and will be useful for probing chemical evolution of the s-process products in various populations of the Milky Way.
Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2017. Vol. 844, no 2, article id 145
Keywords [en]
stars: abundances
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
URN: urn:nbn:se:mau:diva-65211DOI: 10.3847/1538-4357/aa7bebISI: 000406652900023Scopus ID: 2-s2.0-85027328996OAI: oai:DiVA.org:mau-65211DiVA, id: diva2:1829605
2024-01-192024-01-192024-01-19Bibliographically approved