Stellar Atmospheric Parameters from Full Spectrum Fitting of Intermediate- and High-resolution Spectra against PHOENIX/BT-Settl Synthetic Stellar Atmospheres

We present a new technique implemented in IDL for determination of the parameters of stellar atmospheres using PHOENIX and BT-Settl synthetic stellar spectra. The synthetic spectra provide good coverage in the T_eff, log(g), [Fe/H], [α/H] parameter space over a wide wavelength range and allow fitting observed spectra of a vast majority of stars. Our procedure also determines radial velocities and stellar rotation and it takes into account flux calibration imperfections by fitting a polynomial continuum. Thanks to using pixel fitting we can exclude certain spectral features which are not present in the models such as emission lines (chromospheric emission in late-type stars or discs around Be stars). We perform a non-linear χ² minimization with the Levenberg-Marquardt method that is applied to the entire spectrum with the exception of areas with peculiarities: emission lines, model shortcomings (incompleteness of the spectral line lists used for the atmospheric model calculation). We compare the results of the analysis of optical spectra from ELODIE and INDO-US stellar libraries.