Physical parameters of seven field RR Lyrae Stars in bootes

Abstract

Strömgren uvby — β photometry is reported for the RR Lyrae stars AE, RS, ST, TV, TW, UU, and XX in Bootes. The physical parameters M/MΘ, log(L/LΘ), MV , log Teff and [Fe/H], have been estimated from the Fourier decomposition of the light curves and the empirical calibrations developed for this type of stars. The obtained [Fe/H] values are compared with those calculated from the ΔS index for some sample stars. It was found that reddening in the zone is negligible compared to that shown by several objects in the same sky zone. From that, distance to the stars was calculated. The variation of the unreddened indexes (b — y)0 and c1 along the pulsational cycle allows the direct comparison with the theoretical grids and, hence, an independent determination of Teff and log g.