COMMISSION 27 OF THE I. A. U.
          INFORMATION BULLETIN ON VARIABLE STARS
                      Number 2416

                                         Konkoly Observatory
                                         Budapest
                                         18 October 1983

                                         HU ISSN 0374-0676



                 V LIGHT CURVE OF CC COMAE



  The eclipsing binary CC Com is a system of W UMa type with the shortest
known period. The first photoelectric observations in the V band were made
by Wenzel (1967). Rucinski (1976) found the elements of this binary from his
UBV observations. Two-colour light curves of CC Com were also obtained by
Zhukov (1976) and by Breinhorst and Hoffmann (1982).
  New light curves in V were obtained with the 60 cm reflector of the
Southern Station of Sternberg Astronomical Institute in April 1983. The mean
error of one observation did not exceed +-0.02m. Figure 1 shows the mean light


                             [FIGURE 1]


curve of CC Com. The times of minimum light observed in 1980 and 1983 are
given in Table I with (O-C)'s calculated by the following ephemeris formula:

        JD_hel. Min I = 2442467.8307 + 0.2206862d*E

where Rucinski's epoch has been taken.

                    Table I
     ------------------------------------
     JD_hel 2444000+  Min         (O-C)
     ------------------------------------
           584.4316   I          -0.0004d
           672.3763   II         +0.0008
          1434.5162   I          +0.0009
          1435.5087   II         +0.0003
          1436.2814   I          +0.0006
     ------------------------------------

  Analysis of all photoelectric observations of CC Com leads to the following
conclusions:
1. The mean light of the variable star in maxima observed in different seasons
varies. This may be due to a physical variability of the third hypothetic
component of the system. It may also be due to a long-period variability of
Wenzel's comparison star "a", but more thorough studies are needed. However,
the differences between the V-values of the comparison star and that of the
control star are about the same in 1975 and 1983 and these are 0.083m and
0.075m, respectively.
2. O'Connell's effect has been found with five light curves in the V-system.
This effect is of cyclic character, moreover it takes place at maximum I
(phase 0.25).
3. The secondary minimum in yellow light had an invariable shape and depth
during the period of the observations of the CC Com (taking into account
the above remark - point 1.)
4. The binary has a variable period but it is difficult to decide on the
nature of the change from the appearance of the (O-C) diagram (see Fig.2).


                              [FIGURE 2]


5. During 1975 I discovered short-lived depressions at the light curve 
together with the colour changing of CC Com. Such depressions are revealed by
the observations of Rucinski (1976) as well. The character of these depressions
and their position at the light curve (phase 0.36-0.38 and 0.84-0.89) enable
us to suppose the existence of nonstationary gaseous streams from the primary
or at least to establish definitely the nonstability of the common envelope
of the system in the vicinity of point L1.
  In conclusion I wish to draw attention to the same peculiarities discovered
by us for the light curves of V 523 Cas, which has characteristics similar
to those of CC Com.





                  G.V. ZHUKOV
              Department of Astronomy
              Kazan University, Kazan 8,
              USSR





References:
Breinhorst, R.A., Hoffmann, M., 1982, Ap. and Sp. Sci. 86, 107 [BIBCODE 1982Ap&SS..86..107B ]
Rucinski, S.M., 1976, Publ.A.S.P. 88, 777 [BIBCODE 1976PASP...88..777R ]
Wenzel, W., 1967, Mitt.Verand.Sterne 4, Heft 3, 60
Zhukov, G.V., 1976, Astron. Tsirk. No. 918, 7 [BIBCODE 1976ATsir.918....7Z ]