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[vsnet-alert 5791] DW Cnc: an exotic system?



DW Cnc: an exotic system?

Dear Colleagues,

    [This message is also sent to vsnet-alert, since the analysis of the
data has revealed that the object is potentially an extremely important,
timely target].

    Rudolf Novak (Brno) has kindly sent an excellent time-series.
The light curve shows large modulations as recorded by the Ouda observation.
After adding Kyoto observations (Mar. 20 and 21), the entire data set
was analyzed.  Although this data are still a partial one, we have
already obtained 1108 data points.

    There is a very gradual fading trend (0.04 mag/d) throughout the
observation.  This fading rate may resemble those of slowly fading
plateau of ER UMa stars.  DW Cnc was once a monitoring target by the
Ouda team, and outbursts with an amplitude of 1 mag were observed.
This suggests that the object is not a true NL-type system, but may
also bear a characteristic of a dwarf nova.

    The period analysis of the combined light curve has yielded multiple
period candidates, as reported.  We have not been able to find a significant
signal above 0.1 d.  Below 0.1 d, there are signals at 0.0756 d, 0.0536 d,
0.0488 d, and 0.0276 d.  The 0.0536 d and 0.0276 d periods are the same
ones as already pointed out.  There may be a hint of beats between these
periods, but if any shorter one of them is a superhump/orbital period,
this system may be an extremely rare system close to the CV period minimum,
or below the period.  Since most of this region is occupied by WZ Sge
systems and other exotic systems like DI UMa, V485 Cen, the present object,
if its short-period nature is confirmed, may become a key object in
understanding the CV evolution regardless of its CV subtype.  Since the
structure of the signals is complex, we recommend observers to take as much
data points and as long time-series as possible!

    Please go on a long run with the VSNET Collaboration team!

Regards,
VSNET Collaboration team

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