The period-luminosity relation for Cepheids derived from multiphase temperature measurements and Cepheids kinematics based on GAIA DR2 data

Abstract

Calibration of the period-luminosity relation (PLR) for Cepheids has always been one of the biggest goals of stellar astronomy. Among a considerable number of different approaches, the Baade-Becker-Wesselink (BBW) method stands in the foreground as one of the most universal and precise methods. We present a new realization of the BBW method which is considered to be the generalization of surface brightness (\citealt{Barnes+Evans+1976}) and \cite{Balona+1977} approaches first proposed by \cite{Rastorguev+Dambis+2010} and described in \cite{Paper1}. One of the main features of this method is using measured effective temperature variations to determine the main parameters of Cepheid, such as distance, radius, luminosity, colour excess, intrinsic colour. We apply this method to 45 Cepheids of Northern sky, for which multiphase temperature data are available. We take into account the effect of shock waves, whose presence in stellar atmosphere distorts the observational data and the calibrations used in this work. Within $0.0-0.87$ phase interval we derived PL relation $<M_V>_I=-(2.67 \pm 0.17)\cdot logP - (1.58 \pm 0.16)$. It was used to calculate the distances, rotation curve and kinematical parameters of the sample of 435 Cepheids with GAIA DR2 proper motions.