PHOTOMETRIC ANALYSIS OF A NEAR-CONTACT BINARY, HL-AURIGAE - EVIDENCE FOR A THIRD BODY

A complete analysis of U, B, V photometric light curves of HL Aurigae is presented. Twelve new precision epochs of minimum light were determ ined. A period study spanning 45 years and utilizing more than 135 tim es of minimum light indicates that the period has remained essentially constant. The photometry has been standardized and our analysis inclu des corrections for interstellar reddening. We find that HL Aurigae is in a semidetached configuration with the primary component having a f illout of 95%. The primary and secondary components have spectral type s of F1 V and G9 V, respectively, and a mass ratio of similar to 0.8. The photometric solution gives a surprisingly large third light amount ing to 18% in V, and 14% in ti and B. Our calculations suggest the pre sence of an unresolved G2 V component separated by less than 340 AU fr om the close pair. Thus, we tentatively conclude that Ilk Aur is in an hierarchical triple star system, i.e., a close pair with a well-separ ated component. (C) 1997 American Astronomical Society.