HL AURIGAE - A NEAR-CONTACT BINARY-SYSTEM

Photoelectric observations of HL Aur were carried out with the 60 cm r eflector of Beijing Astronomical Observatory in 1990 and 1994, and the first photoelectric BV light curves were obtained along with a newly derived ephemeris. The period of the system appears to be constant ove r the past 65 years. Using the Wilson-Devinney program a photometric a nalysis of the B and V light curves is performed. It is evident that H L Aur is a near-contact binary with a mass ratio of q = m(2)/m(1) = 0. 722 +/- 0.011. The primary component of the system is essentially in c ontact with its Roche lobe, while the secondary is detached but nearly in contact with its lobe. It is found that the components of the syst em are slightly evolved and located near the terminal-age main sequenc e. The binary is consistent with the general evolutionary picture for near-contact systems.(1)