The CaT Stellar Library
Mg and TiO Spectral Features at the
A. Javier Cenarro (1) Nicolas Cardiel (2) Alexander Vazdekis (1) Javier Gorgas (2)
(1) Instituto de Astrofisica de Canarias, Tenerife
(2) Universidad Complutense de Madrid
Using the near-infrared CaT spectral stellar library of Cenarro et al. (2001a,b), we have analyzed the behaviours of the Mg line at 8807Å and nearby TiO molecular bands in terms of the stellar atmospheric parameters (effective temperature, surface gravity, and metallicity) of the library stars.
For this purpose, we have defined new spectroscopic indices for both spectral features, namely MgI and sTiO, and computed empirical fitting functions that reproduce the strength of the new indices as a function of the stellar atmospheric parameters. MgI reveals as a good indicator of the Mg abundance, whereas sTiO is a powerful dwarf-to-giant discriminator for cold spectral types.
At this site you will find a additional information to that presented in the above CaT triplet web site. In particular, the library Database has been updated with the MgI and sTiO values, their errors, residuals of the fitting functions, and a compilation of available [Mg/Fe] values. Also, we provide related Software to measure a wide variety of line-strength indices (including MgI and sTiO), and to predict MgI, sTiO and the CaT indices on the basis of their fitting functions (Cenarro et al. 2002; 2009) for a given set of input atmospheric parameters. The latter is particularly suited to be readily implemented into evolutionary population synthesis codes.