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Adding the s-Process Element Cerium to the APOGEE Survey : Identification and Characterization of Ce II Lines in the H-band Spectral Window

Cunha, Katia ; Smith, Verne V. ; Hasselquist, Sten ; Souto, Diogo ; Shetrone, Matthew D. ; Allende Prieto, Carlos ; Bizyaev, Dmitry ; Frinchaboy, Peter ; García-Hernández, D. Anibal and Holtzman, Jon LU , et al. (2017) In Astrophysical Journal 844(2).
Abstract

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 λ1.51 and 1.69 μm). 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= λ/δλ) Fourier Transform Spectrometer (FTS) spectrum of α 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 α... (More)

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 λ1.51 and 1.69 μm). 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= λ/δλ) Fourier Transform Spectrometer (FTS) spectrum of α 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 α Boo as a standard star, with the absolute cerium abundance in α 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.

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stars: abundances
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Astrophysical Journal
volume
844
issue
2
article number
145
publisher
American Astronomical Society
external identifiers
  • scopus:85027328996
ISSN
0004-637X
DOI
10.3847/1538-4357/aa7beb
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English
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no
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2252ba2e-60b8-4c28-98d6-45e9cdcd2606
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2019-05-06 11:43:38
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2020-09-13 07:02:29
@article{2252ba2e-60b8-4c28-98d6-45e9cdcd2606,
  abstract     = {<p>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 λ1.51 and 1.69 μm). 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= λ/δλ) Fourier Transform Spectrometer (FTS) spectrum of α 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 α Boo as a standard star, with the absolute cerium abundance in α 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.</p>},
  author       = {Cunha, Katia and Smith, Verne V. and Hasselquist, Sten and Souto, Diogo and Shetrone, Matthew D. and Allende Prieto, Carlos and Bizyaev, Dmitry and Frinchaboy, Peter and García-Hernández, D. Anibal and Holtzman, Jon and Johnson, Jennifer A. and Jönsson, Henrik and Majewski, Steven R. and Mészáros, Szabolcs and Nidever, David and Pinsonneault, Mark and Schiavon, Ricardo P. and Sobeck, Jennifer and Skrutskie, Michael F. and Zamora, Olga and Zasowski, Gail and Fernández-Trincado, J. G.},
  issn         = {0004-637X},
  language     = {eng},
  month        = {08},
  number       = {2},
  publisher    = {American Astronomical Society},
  series       = {Astrophysical Journal},
  title        = {Adding the s-Process Element Cerium to the APOGEE Survey : Identification and Characterization of Ce II Lines in the H-band Spectral Window},
  url          = {http://dx.doi.org/10.3847/1538-4357/aa7beb},
  doi          = {10.3847/1538-4357/aa7beb},
  volume       = {844},
  year         = {2017},
}