COMMISSION 27 OF THE I. A. U.
          INFORMATION BULLETIN ON VARIABLE STARS
                       Number 3391

                                        Konkoly Observatory
                                        Budapest
                                        25 October 1989

                                        HU ISSN 0374 - 0676


        UNUSUAL OUTBURST OF THE CATACLYSMIC BINARY MV LYRAE


The attention of cataclysmic binary specialists has been focused on MV Lyrae
since its remarkable fading in 1979. Before that date the brightness of the
star was usually in the "high" state (~12.5m): this was interrupted from time
to time in a semiregular manner by phases of "intermediate" state (between 13m
and 15m, cycle length of 325d-455d between minima). After 1979 the star
predominantly remained in the "inactive" (or "low") state (~>17.0m), from which
the brightness in irregular intervals rose to the intermediate level for one to
several months. Some models start out from the assumption that MV Lyrae is
entering or has entered the well-known gap of orbital periods.

For complete long term light-curves of the years 1928 to 1986 and a discussion
see Wenzel and Fuhrmann (1983) and Andronov, Fuhrmann and Wenzel (1988). In
1987 a strong eruption reached almost 14.0m pg, and after subsequent 600 days
of quiescence the brightness even climbed to 13.6m pg in the summer of 1989,
probably the highest value observed since the fading in 1979. The ascent was
accompanied by strong and very fast fluctuations (for instance from 15.3m to
16.7m during 16 minutes at JD 2447648.4). In the figure we give the
light-curve as a continuation of the curves mentioned earlier. It has been
derived from observations on Sonneberg 40 cm astrograph plates and Sky Patrol
plates and might be important for comparison with spectroscopic data or model
considerations. It should be noted that the sporadic measurements of Kraicheva
(1988) and Rosino (1989) are in good agreement with our observations. The B
system of comparison star magnitudes of Andronov and Shugarov (1982) was used;
smaller dots denote uncertain values, the arrows show upper limits of
brightness when the star was invisible on the plates.


                                 [FIGURE 1]



W. WENZEL and B. FUHRMANN
Sternwarte Sonneberg
Zentralinstitut fur Astrophysik
Akademie der Wissenschaften der DDR
DDR-6400 Sonneberg

References:

Andronov, I.L., Shugarov, S.Yu., 1982, Astron. Tsirk. No. 1218, 3. [BIBCODE 1982ATsir1218....3A ]
Andronov, I.L., Fuhrmann, B., Wenzel, W., 1988, Astron. Nachr. 309, 39. [BIBCODE 1988AN....309...39A ]
Kraicheva, Z., 1988, Inf. Bull. Variable Stars, No. 3210.
Rosino, L., 1989, IAU Circ., No. 4834. [BIBCODE 1989IAUC.4834....2R ]
Wenzel, W., Fuhrmann, B., 1983, Mitt. Veranderl. Sterne, 9, 175. [BIBCODE 1983MitVS...9..175W ]