High precision effective temperatures for 181 F-K dwarfs from line-depth ratios

Line depth ratios measured on high resolution ( ...), high  S/N echelle spectra are used for the determination of precise effective temperatures of 181 F, G, K Main Sequence stars with about solar metallicity ( ...). A set of 105 relations is obtained which rely  ...on ratios of the strengths of lines with high and low excitation potentials, calibrated against previously published precise (one per cent) temperature estimates. The application range of the calibrations is 40006150 K (F8V-K7V). The internal error of a single calibration is less than 100 K, while the combination of all calibrations for a spectrum of  S/N=100 reduces uncertainty to only 5-10 K, and for S/N=200 or higher - to better than 5 K. The zero point of the temperature scale is directly defined from reflection spectra of the Sun with an uncertainty about 1 K. The application of this method to investigation of the planet host stars properties is discussed.