ИСТИНА

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 Teff, logg, [Fe/H], [alpha/H] parameter space over a wide wavelength range and allow to fit 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 chi2 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 take into account systematic errors of the surface gravity estimates introduced by synthetic atmospheres by applying a correction computed from the comparison of our results with those obtained using asteroseismology. We present the comparative statistical analysis of optical spectral libraries ELODIE, INDO-US, MILES, UVES-POP, and a new near-infrared Las Campanas Stellar Library and discuss prospective applications of our technique.