COMMISSION 27 OF THE I. A. U.
          INFORMATION BULLETIN ON VARIABLE STARS
                       Number 3472

                                           Konkoly Observatory
                                           Budapest
                                           6 June 1990

                                           HU ISSN 0374 - 0676



    THE UNIQUE MANIFESTATION OF THE MATTER OUTFLOW IN THE ECLIPSING

                   BINARY SYSTEM V 361 Lyr


   The variable star V 361 Lyr was mentioned as an ordinary RR Lyr type
star in the third edition of the General Catalogue of Variable Stars. Its
period was unknown at that time. The photographic light curve obtained by
one of us (M.G.) revealed the eclipsing nature of this object with periodic
light variations (P=7.5h). The shape of the light curve of V 361 Lyr is similar
to that of beta Lyr systems but in the case of V 361 Lyr the light maxima 
differ by 0.5 mag. from each other what is incompatible with our knowledge
about beta Lyr type and similar systems. Light curves with different maxima
are observed in the case of eclipsed cataclysmic variables (CV) but the
"hump" on CV light curves is observed just before the primary minimum and
is due to the bright spot on an accretion disk around the white dwarf. On
the contrary, the more prominent maximum on the light curve of V 361 Lyr is
Max I after the primary minimum. As to our knowledge, there are no other
binaries with similar light curves. So we decided to carry out photoelectric 
photometry of the object to clarify the situation.
   Classical CVs are specified by an UV excess in their energy distribution 
and H-alpha emission in the spectrum. Observations of V 361 Lyr have not
revealed such peculiarities. Colour indices of V 361 Lyr indicated a 
spectrum ~ K.
   During the last 4 years detailed B, V light curves and a somewhat worse
U light curve have been obtained (see Fig. 1). The light curve of V 361 Lyr
can be presented by a sinusoidal wave with the superimposed minima due to
eclipses. The difference in maxima heights is then due to the fact that Max
I occurs almost in the maximum phase of the sinusoid whereas Max II - in
the end of decline.
   The colour index in the primary minimum (B-V=0.92) is very close to
those in the secondary one (B-V=0.85m). In the "hump" (Max I) the colour 
indices are B-V=0.59m, U-B=-0.10m. The light in both eclipses (Min I and Min II)
seems to come from the same, more luminous companion. The secondary companion 
is assumed to be more evolved (less luminous), with nonuniform temperature 
distribution on the surface. The simplified scheme of the binary model
is shown in Fig. 2 where the secondary component (on the right) is accreting 
matter from the primary component, and a bright spot is formed as a
result of this accretion in the place of accreting matter shock onto the
surface. The bright spot can explain a sinusoidal shape of the light curve
(Fig. 1). During the primary minimum (phi =0.0 p) the spot and the main part of
the luminous companion are hidden from the observer (see Fig. 2). Further,
on the ascending branch, the bright star appears gradually from behind its
companion, conditions for the spot appearance become better and better and
at the phase phi =0.35 p of the orbital period we can see the spot in the best
way (Max I). After this an occultation of the spot by the bright star begins
and becomes total at the orbital phase phi =0.5 p. Subsequently, the spot 
appears again and becomes brightest at the phase phi = 0.65 p (Max II). At the
phase phi =0.80 p the spot disappears again.

V361 Lyr

  Min I = 2444461.3865 + 0.3096149 E

                               [FIGURE 1]

          Figure 1. The light curves of the binary V 361 Lyr

                               [FIGURE 2]

          Figure 2. The model of the binary system V 361 Lyr


   Let us remember that CVs have a hump before the primary minimum which
is explained by the spot on an accretion disk around the white dwarf. In the
case of CVs the matter flows from the secondary companion (red dwarf) to the
primary one (white dwarf surrounded by the accretion disk). On the contrary,
in the binary system V 361 Lyr matter flows from the more luminous star to
its companion and forms on it an extended spot being responsible for an 
extraordinary shape of the light curve of the binary V 361 Lyr.
   We have placed both components on the colour-colour diagram (see Fig.
3). The magnitude of the bright star is V=14.25, the colour indices are
B-V=+0.85m, U-B=+0.50m which correspond to the spectrum K1. The companion (V=
16.1m) with the colour index B-V=+1.1 m is apparently classified as K4V. The
mean spot colour indices are B-V=+0.3, U-B=-0.2, its temperature is 7000 -
8000 K.
   The binary system V 361 Lyr is assumed to be observed at the first mass
exchange evolutionary stage when the brighter and more massive star is 
outflowing to its low-mass companion. A number of such binaries must be 
considerably less than those at the second mass exchange stage (i.e., CVs), 
after the common envelope phase and shrinkage of the system. The first mass 
exchange can be realized only in the binaries with initially small separations
between the components. Hence it is rather serendipitous chance to observe
such a system.
   V 361 Lyr is obviously a binary system worthy of further photometric
and detailed spectroscopic investigation.


                             [FIGURE 3]

              Figure 3. The colour-colour diagram



  S.Yu. SHUGAROV, V.P. GORANSKIJ
  M.P. GALKINA, N.A. LIPUNOVA
Sternberg State Astronomical Institute,
   13, Universitetskij Prosp., Moscow
State University, 119899, Moscow, USSR