The Chemical Compositions Of Very Metal-Poor Stars Hd 122563 And Hd 140283: A View From The Infrared

WOS: 000372305700015
From high resolution (R similar or equal to 45,000), high signal-to-noise ratio (S/N > 400) spectra gathered with the Immersion Grating Infrared Spectrograph (IGRINS) in the H and K photometric bands, we have derived elemental abundances of two bright, well-known metal-poor halo stars: the red giant HD 122563 and the subgiant HD 140283. Since these stars have metallicities approaching [Fe/H] = -3, their absorption features are generally very weak. Neutral-species lines of Mg, Si, S and Ca are detectable, as well as those of the light odd-Z elements Na and Al. The derived IR-based abundances agree with those obtained from optical-wavelength spectra. For Mg and Si the abundances from the infrared transitions are improvements to those derived from shorter wavelength data. Many useful OH and CO lines can be detected in the IGRINS HD 122563 spectrum, from which derived O and C abundances are consistent to those obtained from the traditional [O I] and CH features. IGRINS high resolutions Hand K-band spectroscopy offers promising ways to determine more reliable abundances for additional metal-poor stars whose optical features are either not detectable, or too weak, or are based on lines with analytical difficulties.
NSFNational Science Foundation (NSF) [AST-1211585]; Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [112T929]; NSF-CAREER grantNational Science Foundation (NSF)NSF - Office of the Director (OD) [AST-1255160]; US National Science Foundation of the University of Texas at Austin [AST-1229522]; Korean GMT Project of KASI
This study has been supported in part by NSF grant AST-1211585 to C.S., by The Scientific and Technological Research Council of Turkey (TUBITAK, project No. 112T929) to M.A, and by NSF-CAREER grant AST-1255160 to A.F. This work used the Immersion Grating Infrared Spectrograph (IGRINS) that was developed under a collaboration between the University of Texas at Austin and the Korea Astronomy and Space Science Institute (KASI) with the financial support of the US National Science Foundation under grant AST-1229522, of the University of Texas at Austin, and of the Korean GMT Project of KASI.