Chemical Compositions of Evolved Stars from Near-infrared IGRINS High-resolution Spectra. I. Abundances in Three Red Horizontal Branch Stars
Makaleler > Tam Makale · 2018
Yazarlar: Melike AFŞAR, Christopher Sneden, Michael P. WOOD, James E. LAWLER, Zeynep BOZKURT, Gamze Bocek TOPCU, Gregory N. MACE, Hwihyun KİM, Daniel T. JAFFE
The Astrophysical Journal, SCI Expanded İndekslerine Giren Dergi, Uluslararası, Wos, 2018, cilt 865, ss 44-44
Özet
Abstract We have derived elemental abundances of three field red horizontal branch stars using high-resolution (R ≃ 45,000), high signal-to-noise ratio (S/N ≳ 200) H- and K-band spectra obtained with the Immersion Grating Infrared Spectrograph (IGRINS). We have determined the abundances of 21 elements, including α (Mg, Si, Ca, S), odd-Z (Na, Al, P, K), Fe-group (Sc, Ti, Cr, Co, Ni), neutron-capture (Ce, Nd, Yb), CNO-group elements. S, P, and K are determined for the first time in these stars. H- and K-band spectra provide a substantial number of S i lines, which potentially can lead to a more robust exploration of the role of sulfur in the cosmochemical evolution of the Galaxy. We have also derived 12C/13C ratios from synthetic spectra of the first-overtone 12CO (2–0) and (3–1) and 13CO (2–0) lines near 23440 Å and 13CO (3–1) lines at about 23730 Å. Comparison of our results with the ones obtained from the optical region suggests that the IGRINS high-resolution H- and K-band spectra offer more internally self-consistent line abundances of the same species for several elements, especially the α-elements. This in turn provides more reliable abundances for the elements with analytical difficulties in the optical spectral range.