COMMISSION 27 OF THE I.A.U.
            INFORMATION BULLETIN ON VARIABLE STARS
                         Number 1201

                                                 Konkoly Observatory
                                                 Budapest
                                                 1976 November 9 


                           HS AURIGAE

Detached main-sequence eclipsing binaries of type later
than the sun are very rare among known systems, nearly all the
later type detached binaries being subgiants of the kind listed
in IBVS 1083. The only detached system with main-sequence components 
later than the sun that has been analyzed is YY Gem (M1).
   Spectrograms of the 10th magnitude eclipsing binary
HS Aur obtained at the Lick Observatory show this system to consist
of two similar stars of type G8V. HS Aur had been classified as
a G star by Gotz and Wenzel (1962) and by McDonald (1964). The
period is 9.8d rather than the GCVS value of 4.9d, so that the
two minima of the light curve must be of approximately equal
depth. Emission lines of Ca+ are not present in the spectrum.
Young and Koniges (1976) have shown that emission is usually 
absent in main-sequence systems with periods as long as 10 days.
   The principal purpose of this note is to call attention
to the importance of obtaining a definitive photoelectric light
curve of HS Aur on a standard color system. A complete analysis
of the combined photometric and spectrographic observations
should give a fundamental set of stellar parameters in a region
of the H-R diagram heretofore provided definitely only by the
more massive components of the visual binaries xi Boo and 70 Oph.


                                     D.M. POPPER

                                     Department of Astronomy
                                     University of California
                                     Los Angeles



References:

Gotz, W. and Wenzel, W. 1962. M.V.S. 626
McDonald, D.D. 1964. Publ.Leander McCormick Observ. XII. Pt. 4
Young, A. and Koniges, A 1976 (in press)