COMMISSION 27 OF THE I. A. U.
          INFORMATION BULLETIN ON VARIABLE STARS
                       Number 3386

                                          Konkoly Observatory
                                          Budapest
                                          18 October 1989

                                          HU ISSN 0374 - 0676


                      Be VARIABLE 59 Cyg 
               RAPID LIGHT VARIATIONS DETECTED


V832 Cyg (59 Cyg, HR 8047, HD 200120), a B1Ve star, is a member of the Cyg OB7
association and is the brightest component of a multiple system of stars ADS
14526. It forms a common-motion pair with component B (4.4m fainter) at 20.1".
Component C at 26" is optical, and there is also component D at 38". McAlister
et al. (1984) discovered a speckle-interferometric component a at 0.21" and
Tarasov and Tuominen (1987) suggested that V832 Cyg may be a spectroscopic
binary with an orbital period of 29.14 days. V832 Cyg is also a famous
spectral variable, for which correlated optical and UV long-term spectroscopic
changes were documented (see Doazan et al. 1989 and references therein).

For a long time, V832 Cyg has been known as a long-term light variable. GCVS
quotes a range from 4.5 to 4.9m. Lynds (1959) observed a steady decline of
brightness from 4.66m to 4.76m between June and October 1958 and there are some
other photometric observations scattered in the astronomical literature.

We observed the star as one of the targets of the long-term observing campaign
on bright Be stars initiated and organized by Harmanec, Horn and Koubsky
(1981). UBV observations were secured at Hvar in 1985 and 1988 and BV
observations were obtained in Toronto in 1986, 1987, and 1988. The 1986
Toronto observations were already published by Percy et al. (1988).

In all cases,

HD 199311 V=6.689m, B-V=+0.086m, U-B=+0.086m

and

HD 199479 V=6.846m, B-V=+0.033m, U-B=-0.220m

served as the comparison and check (their UBV values quoted originating from
the homogenized Hvar all-sky photometry). The check star was observed as
frequently as the variable.


                               [FIGURE 1]


Figure 1 is the plot of the individual V and B observations of V832 Cyg and the
check, HD 199479, versus time for the 1985 observing season. Figure 2 is the
same diagram for the 1988 data (symbols * and square are used to distinguish
Hvar and Toronto data, respectively).


                               [FIGURE 2]


Although some of the data are somewhat noisier than usual, it is clearly seen
that while the variable was relatively quiet on a time scale of days and
shorter in 1985, rapid variations up to 0.1m were detected in 1988. The 1986
and 1987 Toronto data show no significant variations within the seasons (i.e.
sigma(variable)=sigma(check)), but the variable was about 0.02m brighter in V
and B in 1987 relative to 1986. The corresponding mean values are

1986 V=4.780m, B=4.664m; 42 observations, and
1987 V=4.759m, B=4.645m; 7 observations;

typical r.m.s. error of the means being 0.0075m. Our data thus clearly
indicate a gradual secular brightening of the star from 1985 to 1988. They are
not numerous enough and well distributed in time, however, to warrant a
meaningful period analysis. We only want to alert the Be star observers that
further monitoring of this intriguing object would be very desirable. We plan
a detailed study of the photometric behaviour of V832 Cyg in the future.

Acknowledgement

JRP acknowledges the support of the Natural Sciences and Engineering Research
Council of Canada.


P. HADRAVA, P. HARMANEC          J.R. PERCY
J. HORN, P. KOUBSKY, S. KRIZ     Department of Astronomy
Astronomical Institute, CSAV     University of Toronto
25165 Ondrejov                   Toronto, Ontario
Czechoslovakia                   M5S 1A1 Canada

H. BOZIC
Hvar Observatory
Faculty of Geodesy
University of Zagreb
41000 Zagreb, Jugoslavia

References:

Doazan V., Barylak M., Rusconi I., Sedmak G., Thomas R.N., Bourdonneau B.
   1989 Astrophys. J. 210, 249 [BIBCODE 1989A&A...210..249D ]
Harmanec P., Horn J., Koubsky P. 1981 Be Star Newsletter No. 2, 3
Lynds C.R. 1959 Astrophys. J. 130, 577 [BIBCODE 1959ApJ...130..577L ]
McAlister H.A., Hartkopf W.I., Gaston B.J., Hendry E.M., Fekel F.C. 1984
   Astrophys. J. Suppl. 54, 251 [BIBCODE 1984ApJS...54..251M ]
Percy J.R., Coffin B.L., Drukier G.A., Ford R.P., Plume R., Richer M.G.,
   Spalding R. 1988 Publ. Astron. Soc. Pacific 100, 1555 [BIBCODE 1988PASP..100.1555P ]
Tarasov A.E., Tuominen I. 1987 Publ. Astron. Inst. Czechosl. Acad. Sci. No.
   70, 127 [BIBCODE 1987PAICz..70..127T ]