2010MNRAS.406..486B

A photometric calibration of Kurucz static model atmospheres is used to obtain the following parameters of RR Lyrae stars: variation of stellar angular radius θ, effective temperature T_e, gravity g_e as a function of phase, interstellar reddening E(B - V) towards the star and atmospheric metallicity M. Photometric and hydrodynamic conditions are given to find the phases of pulsation when the quasi-static atmosphere approximation (QSAA) can be applied. The QSAA is generalized to a non-uniformly moving spherical atmosphere, and the distance d, mass and atmospheric motion are derived from the laws of mass and momentum conservation. To demonstrate the efficiency of the method, the UBV(RI)_C_ photometry of SU Dra was used to derive the following parameters: [M] = -1.60±0.10 dex,, equilibrium luminosity L_eq= 45.9±9.3 L_☉andT_eq= 6813±20 K.