COMMISSION 27 OF THE I. A. U.
          INFORMATION BULLETIN ON VARIABLE STARS
                      Number 2763

                                      Konkoly Observatory
                                      Budapest
                                      24 July 1985

                                      HU ISSN 0374- 0676


      ON THE ORBITAL PERIOD OF A PROBABLE POLAR HV ANDROMEDAE



 The cataclysmic variable HV Andromedae (= S 10777) was discovered by
Meinunger (1975) and classified by him as an irregular variable of Ia type.
Meinunger (1980) supposed that the object belongs to AM Her-type stars based
on photometric and spectral observations. Unfortunately, until now there are
no data on polarisation, spectral changes and rapid variability.

 HV Andromedae was investigated using 94 ORWO ZU-21 photographic plates,
which were obtained on the AZT-3 telescope of Astronomical observatory of
Odessa State University in autumn of 1984. The magnitudes of comparison stars
were taken from Meinunger (1975).
 Individual light curves of HV Andromedae are shown in Figure 1. The
magnitude changes with a 81-minute cycle, but periodic variations are
perturbed by strong irregular changes. Because the duration of the exposure
is 1/7 of the period, the observed light curves are essentially deformed. The
magnitude of brightness variations in some nights may be greater than 1mag.
As for AM Herculis (Andronov, et al., 1980), the shape of the light curve
varies not only from night to night, but also from cycle to cycle. When
luminosity decreases, the amplitude of magnitude variations increases, that is
usual for "intermediate state" of polars (Andronov, 1984).
 By our observations, there was a tendency of brightness increase from
night to night, that corresponds to the upper part of ascending branch of
luminosity curve. During 16d the system brightened by ~0.3mag, which is in
fairly good agreement with Meinunger's (1975) data. By his data the duration
of the ascending branch on the luminosity curve is ~200d long, that is greater
than 30-80d for AM Herculis.
 On the light curve obtained on J.D. 2446007 one may suppose the beating
of two similar in magnitude oscillations with the periods of approximately
0.056d and 0.062d. But because of the accuracy of photographic observations
it is impossible to draw a certain conclusion.
 The periodogram for HV Andromedae is shown in Figure 2. The values of
periods of 0.055994d, 0.055404d, 0.056600d, 0.055043d, 0.057010d ,0.055627d,


                               [FIGURE 1]

 Figure 1: Individual light curves of HV Andromedae. Uncertain 
 observations are marked by crosses, ephemerides for times of minima are 
 marked by arrows.


are possible. As a test parameter we used the dispersion of phases of times
of minima which were derived from our observations and are shown in Table I.

                                Table I

  H.J.D.          E        O-C             H.J.D.           E        O-C
2445991.4984      0      -0.0076d       2446001.5319       179      0.0030d
   5991.5602      1      -0.0018           6001.5818       180     -0.0031
   5991.6220:     2       0.0040           6001.6327       181     -0.0082
   5991.6767      3       0.0027           6001.7053:      182      0.0084
   5991.7252      4      -0.0048           6007.4057       284     -0.0026
   5996.4916     89       0.0021           6007.4605       285     -0.0038
   5996.6212     91       0.0198           6007.5256       286      0.0053
                                           6007.5996:      287      0.0233


                                 [FIGURE 2]

 Figure 2: The periodogram for HV Andromedae. The upper curve was 
 obtained for 12 times of minima, the lower one - for 15 (using also 
 observations marked by ":").


Uncertain minima are marked by a symbol ":" . From conjugate periods it is not
easy to choose the true one, but the most probable elements are as follows:

       Min.H.J.D. = 2445991.506 + 0.055994d E.
                           +/-3      +/-18

For choosing the true period, new observations are needed.

  The data indirectly confirms that HV Andromedae belongs to polars, but
polarimetric data are needed for the adequate classification. In addition
the star is an interesting object for investigations in X-ray and W regions;
for photometric, polarimetric, and spectral studies.


                     I.L. ANDRONOV and M.I. BANNY
                     Odessa State University
                     T.G. Shevchenko Park
                     Odessa 270014 USSR



References:

Andronov, I.L., 1984, Ph.D. thesis, Leningrad State University 22pp.
Andronov, I.L., Vasilieva, S.V., Tsessevich, V.P., 1980, Astron. Tsirk.,
      1142, p.5. [BIBCODE 1980ATsir1142....5A ]
Meinunger, L., 1975, Mitt.Ver.Sterne, 7, I, p.1. [BIBCODE 1975MitVS...7....1M ]
Meinunger, L., 1980, Inform.Bull.Var.Stars, No. 1795.