[vsnet-alert 612] EG Cnc: a WZ Sge-type star or a more usual SU UMa?

[Taichi Kato <tkato>]

   Congratulations to K. Matsumoto and the CBA team on their independent
discoveries of "superhumps" (regardless of oribital or genuine).  The short
period and large outburst amplitude (~7.2 mag) strongly favor EG Cnc as
a new member of WZ Sge, while the development of "outburst (super)humps"
still needs to be more carefully treated, since at least some of "more usual"
SU UMa-type stars definitly show ever-decreasing -- even nearly disappering
-- amplitudes of superhumps while they are still in their plateau stage.
Watanabe's sighting (vsnet-alert 601), and one more sighting by N. Makiguchi
may be suggestive of existence of normal outbursts -- more resembling
long outburst-cycle SU UMa-type dwarf novae like V1028 Cyg?  In these cases
double-humped low amplotude modulations also appeared in the earliest
stage of a superoutburst, which seem to differ from early superhumps in
"genuine" WZ Sge stars in that the modulations do not always seem to represent
orbital periods: sometimes longer than the later superhump period.
Although I strongly expect and favor everything WZ Sge or AL Com in EG Cnc
also, the truth should lie in the course presently ongoing.  Huruhata's
1977 record suggests the star may show a plateau or a halt at around eight
days after the maximum; a 0.3 mag short-term variation in his record may
be indicative of fully grown superhumps, considering the accuracy of his
photographic measures.  The wavefront of the waited signal may be just
intruding the solar system.

Regards,
Taichi Kato

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