AUTOMATED DETERMINATION OF [Fe/H] AND [C/Fe] FROM LOW-RESOLUTION SPECTROSCOPY

We develop an automated spectral synthesis technique for the estimation of metallicities ([Fe/H]) and carbon abundances ([C/Fe]) for metal-poor stars, including carbon-enhanced metal-poor stars, for which other methods may prove insufficient. This technique, autoMOOG, is designed to operate on relatively strong features visible in even low- to medium-resolution spectra, yielding results comparable to much more telescope-intensive high-resolution studies. We validate this method by comparison with 913 stars which have existing high-resolution and low- to medium-resolution to medium-resolution spectra, and that cover a wide range of stellar parameters. We find that at low metallicities ([Fe/H] less than or similar to -2.0), we successfully recover both the metallicity and carbon abundance, where possible, with an accuracy of similar to 0.20 dex. At higher metallicities, due to issues of continuum placement in spectral normalization done prior to the running of autoMOOG, a general underestimate of the overall metallicity of a star is seen, although the carbon abundance is still successfully recovered. As a result, this method is only recommended for use on samples of stars of known sufficiently low metallicity. For these low- metallicity stars, however, autoMOOG performs much more consistently and quickly than similar, existing techniques, which should allow for analyses of large samples of metal-poor stars in the near future. Steps to improve and correct the continuum placement difficulties are being pursued.

Physics Frontier Centers/JINA: Joint Institute for Nuclear Astrophysics

US National Science Foundation (NSF)

Brazilian institutions FAPESP

CNPq

Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)

INAF cofin 2006

Deutsche Forschungsgemeinschaft - DFG cluster of excellence ""Origin and Structure of the Universe""

American Society for Transplantation (AST) [AST 00-98508]

American Society for Transplantation (AST) [AST 00-98549]

American Society for Transplantation (AST) [AST 04-06784]

American Society for Transplantation (AST) [AST 07-07776]

[PHY 02-16783]

[PHY 08-22648]