On the duplicity of cool giant and supergiant variable stars

Abstract

From the analysis of photometric, colorimetric and polarimetric data it follows that high luminosity red variable stars are divided into two groups: group I - double stars with brightness variation periods of more than 480 days, group II - single stars with periods less than 480 days. Moreover, double stars possess: a) high coefficients of correlation between brightness V and U - B, B - V colors; b) relatively low values of U - B ( 1.5) and often those are associated with maser sources.