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Published November 10, 2007 | Published
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Chemical Abundances of Luminous Cool Stars in the Galactic Center from High-Resolution Infrared Spectroscopy

Cunha, Katia
Sellgren, Kris
Smith, Verne V.
Ramirez, Solange V.
Blum, Robert D.
Terndrup, Donald M.
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Abstract

We present chemical abundances in a sample of luminous cool stars located within 30 pc of the Galactic center. Abundances of carbon, nitrogen, oxygen, calcium, and iron were derived from high-resolution infrared spectra in the H and K bands. The abundance results indicate that both [O/Fe] and [Ca/Fe] are enhanced, respectively, by averages of +0.2 and +0.3 dex, relative to either the Sun or the Milky Way disk at near-solar Fe abundances. The Galactic center stars show a nearly uniform and nearly solar iron abundance. The mean value of A(Fe) = 7.59 ± 0.06 agrees well with previous work. The total range in Fe abundance among Galactic center stars, 0.16 dex, is significantly narrower than the iron abundance distributions found in the literature for the older bulge population. Our snapshot of the current-day Fe abundance within 30 pc of the Galactic center samples stars with an age less than 1 Gyr; a larger sample in time (or space) may find a wider spread in abundances.

Additional Information

© 2007 The American Astronomical Society. Received 2007 May 11; accepted 2007 July 16. K. C. thanks Ken Freeman for discussions. K. S. thanks Marc Pinsonneault and Rick Pogge for discussions. These findings are based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Particle Physics and Astronomy Research Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), CNPq (Brazil), and CONICRT (Argentina). This paper uses data obtained with the Phoenix infrared spectrograph, developed and operated by the National Optical Astronomy Observatory. These findings are also based on observations at the Infrared Telescope Facility, which is operated by the University of Hawaii under cooperative agreement NCC 5-538 with the National Aeronautics and Space Administration, Science Mission Directorate, Planetary Astronomy Program. This work is also supported in part by the National Science Foundation through AST02-06331 (K.S., S.V. R.) andAST06-46790(K. C.,V.V.S.), and NASA through JPL Agreement 1265550 (K. S.) and NAG 05- 9213 (K. C., V. V. S.).

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