THE LICK/SDSS LIBRARY. II. [Ca/Fe] AND [Mg/Fe] IN F, G, AND K STARS FROM SDSS-DR7
- INAF-Osservatorio Astronomico di Trieste, Via G.B. Tiepolo 11, I-34131 Trieste (Italy)
- Instituto Nacional de Astrofisica, Optica y Electronica, Luis Enrique Erro 1, 72840 Tonantzintla, Puebla (Mexico)
We analyzed the spectra of 17,600 F, G, and K stars extracted from the seventh Sloan Digital Sky Survey Data Release (SDSS-DR7) database in order to derive ([{alpha}/Fe]), [Ca/Fe], and [Mg/Fe] ratios. Particular attention has been devoted to estimating homogeneous and self-consistent atmospheric parameter values, T{sub eff}, log g, and [Fe/H], by comparing synthetic and observational Lick/SDSS indices. We present results for the sub-sample of more than 4000 spectra whose overall quality allowed us to derive fairly accurate stellar atmospheric parameter values and, therefore, reliable abundance ratios. A Monte Carlo approach was adopted to evaluate both the errors in the observational Lick/SDSS indices and in the derived parameter estimates. The analysis of the trends of [Ca/Fe] and [Mg/Fe] versus [Fe/H] pointed out that (1) the [Ca/Fe] and [Mg/Fe] ratios increase with decreasing [Fe/H] with different slopes reaching maximum average levels of +0.25 and +0.40 dex at [Fe/H] {approx_equal} -1.75, respectively; (2) our sample contains, at a given [Fe/H], stars characterized by significantly different amounts of {alpha}-enhancement, thus belonging to different Galactic populations; and (3) the analyzed sample shows a predominance of thick disk stars for [Fe/H] > - 0.5 and the presence of stars belonging to the 'high-{alpha}' halo population for -2.0 < [Fe/H] <-0.5.
- OSTI ID:
- 21574843
- Journal Information:
- Astrophysical Journal, Vol. 730, Issue 2; Other Information: DOI: 10.1088/0004-637X/730/2/117; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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