COMMISSION 27 OF THE I.A.U.
               INFORMATION BULLETIN ON VARIABLE STARS
                            Number 1484

                                                      Konkoly Observatory
                                                      Budapest
                                                      1978 October 16


     WY Cnc - A PUZZLING SMALL-SCALE ALGOL SYSTEM

The variability of the short period (0d.829) eclipsing binary
WY Cnc was recognized by Hoffmeister (1949), though it was
Kippenhahn (1953) who first pointed out its Algol type pattern
of light variability. Chambliss (1965) published a two colour
photoelectric investigation of the system as a result of which
he was able to produce a set of geometric elements. The system
has been observed subsequently by Ahnert (1973) and again by
Chambliss (1975), the former having reported essential constancy
of the orbital period over a forty year interval.
   Popper (1976), who gave the predominant spectral type as G5,
included the star in a list of close binaries exhibiting the H
and K lines in emission, as a result of which, perhaps, the star
has been included in the "short period" group of RS CVn like
binaries studied by Hall (1976). One of the more salient puzzles
appears at this stage in the actual appearance of the light curve,
i.e., the deep primary and very low level of proximity induced
photometric distortion - the short period and intermediate spectral
type notwithstanding.
   Unfortunately, there appears to be no published radial velocity
curve for the system. Popper (1976) identifies the source of the
emission lines to be the primary and notes (private communication)
that in this respect it is the only exception in his list. This
point is perplexing, however, since according to analysis of
Chambliss (1965) it is the slightly more luminous star which 
remains uneclipsed at the occultation (primary) minimum.
   From some preliminary results obtained with the 3 prism 
Cassegrain spectrograph of the 74 inch reflector at Kottamia we can
make a tentative identification at elongation of weak emission
features in the H and K lines, though we would tend not to 
associate them, on the basis of apparent Doppler shift, with the
predominant G type (primary) spectrum, but we have no conclusive
measurements about this as yet.

                    [FIGURE 1]

                    [FIGURE 2]

   Another problem concerning this primary star is its small
size. Even if the mass of the system were as much as 6 solar
masses the Chambliss solution yields the primary radius to be
still only two thirds that of the Sun.
   We have re-observed the system photoelectrically in B and
V colours using the photometric arrangement described by Sadik
(1978). The main comparison star was BD 27d1700 with occasional 
checks being made on BD 27d1699. The phases of WY Cnc were
computed from the ephemeris

          JD Hel Min I = 2426352.3895 + 0d.82931722 E.

   We can confirm the essential features of the light curve as
given by Chambliss, though there may be some minor differences.
It is planned to re-analyze the system, and to obtain more
spectrograms when the star again becomes favourably placed for
observation.


                    N.S. AWADALLA and E. BUDDING

                      Department of Astronomy,
                     University of Manchester,
                        Manchester, England.



References:

Ahnert, P.: 1973, MVS, Sonneberg 6, 107
Chambliss, C.R.: 1965, Astron.J. 70, 741 [BIBCODE 1965AJ.....70..741C ]
Chambliss, C.R.: 1975, I.B.V.S. No. 1029
Hall, D.S.: 1976, Proc. I.A.U.Coll. No. 29 (Budapest), Part I, p. 287, Reidel,
    Dordrecht [BIBCODE 1976ASSL...60..287H ]
Hoffmeister, C.: 1949, Astron. Abh. 12, 422
Kippenhahn, R.: 1953, Nachr. Astr. Zentralstelle 7 Ann. No. 3
Popper, D.M.: 1976, I.B.V.S. No. 1083
Sadik, A.R.: 1978, I.B.V.S. No. 1381