3. The peculiarity of present low state
MV Lyr is currently in a low brightness state which has lasted three years. It has not much resembled the previous one, which lasted 10 years. To demonstrate this, we present the overall light curve of MV Lyr over the last 20 years (Fig. 1). This light curve was partially published (Pavlenko 1998b), but is here augmented by data from VSNET and VSOLJ, available at the server ftp://ftp.kusastro.kyoto-u.ac.jp, as well as our own new observations. The times of detailed study in the bright state are marked by arrows.
As mentioned above, the previous low state was punctuated by outbursts of different amplitude (Shugarov & Pavlenko 1998). The jumps in brightness reached no higher than , never quite to the high state level. At the present low state the small outbursts have not been observed, whereas large ones occur every days. In all there were five such outbursts (and the sixth one is observing at present time). In accordance with the observed frequency of outburst, one could expect such an outburst within , but the lack of data does not permit us to conclude whether the expected outburst occurred.
The frequency of these outbursts agrees with the Parenago-Kukarkin relation for dwarf novae (Kukarkin & Parenago 1934, Kholopov & Efremov 1976, Warner 1987) between amplitude and recurrence time. However, its decay time of is far too long to be consistent with the characteristic dwarf novae decay times given by Bailey (1975) and Warner (1987).
In contrast to the previous low state (), the peak brightness of outbursts is now similar to the brightness of the true high state. So the description of the present state is somewhat ambiguous: regular outbursts superposed on the low state, or regular fadings from the high to the low state.
© European Southern Observatory (ESO) 1999
Online publication: March 1, 1999