COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 2698

                                   Konkoly Observatory
                                   Budapest
                                   27 March 1985

                                   HU ISSN 0374 - 0676




   THE SYMBIOTIC STAR Z ANDROMEDAE: UBV PHOTOMETRY DURING 1974 - 1984



Z And is one of the best known symbiotic stars. Its light curve is an
alternation from the periods of enhanced activity (Deltam_pg ~~ 2m-4m) to relative
quietness (Deltam_pg < 1m) (Mayall, 1969; Mattei, 1978).
UBV photometry of Z And has been resumed at the Crimean Astrophysical
Observatory since 1981 (Belyakina, 1970).

                           [FIGURE 1]

  This variable was in quiet state from 1974 till 1984. The results of
Meinunger's (1981) (x), Yudin's (1982) (Delta) and our (o) UBV measurements carried
out in this period are presented in Figure 1. Some visual brightness
estimations of this star are also demonstrated here (Delta,o) (Mattei, 1978, 1984;
Morgan, 1984). The V, B, U light curves show simultaneous fluctuations with
the quasi-period equal to 700d and their amplitudes are close to 0.5m, 0.6m
and 1.3m, respectively.
  The observations of Z And being scanty do not permit us to make a detailed
analysis of these light curves. But the shapes of the U and V light curves in
the 1975 minimum and the 1982 maximum are obviously different. It can be 
explained within the framework of a binary model where the red component shows
small variations. The IR photometry confirmed this hypothesis (Yudin, 1982).
  The 1983 minimum in the V light curve is deeper and the corresponding
U light curve is shallower than the preceding ones. It might be caused by the
appearance of the 1984 outburst (Mattei, 1984).




                            T.S. BELYAKINA

                      Crimean Astrophysical Observatory
                        334413 Nauchny, Crimea, USSR





References:

Belyakina, T.S., 1970, Izv. Krimsk. Astrophys. Obs., 41-42, 275. [BIBCODE 1970IzKry..41..275B ]
Mattei, J.A., 1978, J. Royal. Astron. Soc. Canada, 72, 61. [BIBCODE 1978JRASC..72...61M ]
Mattei, J.A., 1984, IAU Circ., No. 3932. [BIBCODE 1984IAUC.3932....3M ]
Mayall, M.W., 1969, J. Royal. Astron. Soc. Canada, 63, 321. [BIBCODE 1969JRASC..63..321M ]
Meinunger, L., 1981, MVS, 9, H. 3, 67.
Yudin, B.F., 1982, Dissertation.