INFRARED LIGHT CURVES AND ABSOLUTE PARAMETERS OF THE ACTIVE BINARY RTANDROMEDAE

We present the first light curves in the infrared J and K filters, obt ained in different runs during 1990, 1991, and 1994. The solutions of these IR light curves together with the previous determinations, gathe red from visual light curves and spectroscopic studies, finally yield stellar parameters that can be accepted with confidence. The study of the (V-lambda) observed colors, by comparison with tabulated colors of normal stars, indicates that they correspond to those expected if RT And components have G0 V and K2 V spectral types. The comparison with ATLAS stellar atmosphere models gives effective temperatures about 600 0 and 4900 K, for the primary and secondary star, respectively. From t he visual-infrared photometry there is no evidence of an IR excess in the system, and its distance is determined to be 103 pc. We have compa red the absolute stellar parameters derived from the light curve solut ions with new evolutionary models for solar composition, and discussed the age and evolutionary state of this binary system. While the mass and radius of the primary star locates it close to the main sequence, with an age of about 1.4X10(9) yr, the secondary star seems to be over sized for its mass, and some sort of interacting episode in the evolut ionary history of this detached binary is not discarded. (C) 1995 Amer ican Astronomical Society.