COMMISSION 27 OF THE I. A. U.
            INFORMATION BULLETIN ON VARIABLE STARS
                        Number 3059


                                             Konkoly Observatory
                                             Budapest
                                             7 August 1987

                                             HU ISSN 0374-0676


               B, V PHOTOMETRY OF ER VULPECULAE

  The double-lined spectroscopic and eclipsing binary ER Vul has received
more attention in recent years, when Hall (1976) included it into the short
period group of RS CVn-type binaries. Many light curves of it were obtained
in order to reveal and understand the cause of the variations. Since 1981
the short period RS CVn binaries ER Vul, UV Psc, and SV Cam have been observed 
at the Ege University Observatory. The light curve variations of the
peculiar eclipsing system ER Vul have been discussed recently by Ibanoglu
et al. (1987). The photometric results of 1984 and 1985 observations are
still in preparation. In this paper we present the 1986 blue and yellow light
curves of the system.
  The observations were obtained with the 48 cm Cassegrain telescope of the
Ege University Observatory. An EMI 9781A photomultiplier and standard B and
V filters were used. HD 200270 was chosen as comparison and HD 200425 as
check star. The differential magnitudes in two colours were taken as variable
minus comparison. These magnitudes were also corrected for atmospheric 
extinction. The following light elements given by Ibanoglu et al. (1985) were
used in computing the phases of the individual observations:


        Min I = J.D. Hel. 2440 182.2621 + 0.69809409dE.


   Two different light curves were obtained with an interval of a month in each
colour. The light curves are shown in Figures 1 and 2. As it is clearly seen
from these Figures the system seems to be too active at the end of June, 1986.
Short-term, non-periodic light fluctuations seem to be the main characteristics
of the system. However, a month later it appears to be fairly quiet. The
system is brighter at the first maximum than it is at the second. The descending
and ascending branches of both minima are generally asymmetric. The mean
brightness of the system reaches its maximum value at about phase 0.35 and it
decreases rapidly until phase 0.6, then, it remains almost constant for a long


                           [FIGURE 1]

   Fig. 1: The blue light curves of ER Vul obtained in 1986.

                           [FIGURE 2]

   Fig. 2: The yellow light curves of ER Vul obtained in 1986.


phase interval, until about phase 0.1. Therefore, it is too difficult to
make any decision about the phase of minima of the wave-like distortion. The
phase of the wave-minima obtained so far were plotted versus years. Despite
the scattering of the points, the wave-like distortion superimposed on the
light curves moves towards the decreasing orbital phase with a period of about
eight months. The nonstationary state of the system ER Vul is studied by
Botsula (1985) who concluded that gaseous matter exists in the system. The
light fluctuations in the light curves may be the result of this event.


                   M.C. AKAN, C. IBANOGLU, Z. TUNCA,
                       S. EVREN and V. KESKIN

                    Ege University Observatory
                    Bornova, Izmir/TURKEY


References;

Botsula, R.A.; 1985, Izv. Astron. Ehngel'gardt Obs. No.49,57. [BIBCODE 1985IzEhn..49...57B ]
Hall, D.S.: 1976, Proc. of IAU Colloq. No.29, Budapest, Part 1, 298. [BIBCODE 1976ASSL...60..287H ]
Ibanoglu, C., Akan, M.C., and Evren, S.:1985, Inf. Bull. Var.Stars, No. 2782.
Ibanoglu, C., Evren, S., and Tunca, Z.: 1987, Astrophys. Space Sci., (in press). [BIBCODE 1987Ap&SS.136..225I ]