SYNTHETIC MEAN COLORS FOR RR LYRAE VARIABLES

Convective pulsating models computed for wide ranges of luminosity and effective temperature (Bone and Stellingwerf 1994) are used together with stellar atmosphere models (Kurucz 1992) to obtain a set of synthetic B - V and V - K mean colors for ab- and c-type RR Lyrae variables. The results clearly show that neither the blue nor the infrared mean colors are representative of the equivalent static value, i.e., the color of the variable if it were a static star, over the whole instability strip. Moreover, it is shown that the discrepancy between synthetic mean colors and static color is a function of the amplitude of the light curve. On this basis, the amplitude corrections to observed mean colors to obtain the color of the underlying static star are derived.