[vsnet-alert 6567] WZ Sge: details of the 9-th rebrightening

[Taichi Kato <tkato>]

WZ Sge: details of the 9-th rebrightening

Dear Colleagues,

   We have received new, very excellent, data from B. Martin.  The data
covered the 9-th rebrightening maximum to early decline, and confirmed
the lengthening of the maximum phase.

   Time-series analysis of the 9-th rebrightening revealed that relatively
broad, but distinct, eclipses appeared slightly earlier than the predicted
eclipses.  The phase 0.7-0.8 hump becomes also prominent.  The overall
appearance of the light curve is double-humped, whose profile strongly
resemble that of quiescent humps (and possibly early superhumps).
The figure is placed on the VSNET WZ Sge page.

   The similar profile during the rebrightening was seen on Aug. 28 (the
4-th rebrightening).  The recent systematic variation of hump/eclipse
profiles during the rebrightening stages seems to support the presence
of a 9-d beat period, seemingly closely related to the "beat phenomenon"
observed during the main superoutburst!  This fact indicates that we
have covered a full precession of the post-superoutburst eccentric disk,
and recorded systematic change of the associated eclipse profile and
hump profile across rebrightening -- the long-wanted observation in
these CVs, and probably the first successful one in WZ Sge-type dwarf nova!
The present success is expected to solve the "enigma" of the WZ Sge-type
post-superoutburst rebrightening!!

   It has become increasingly evident that the present WZ Sge outburst
provides the chance in a thousand in the CV research!  Please keep the
present very excellent and impressive coverage, until the star completely
fades away!

Regards,
Taichi Kato
VSNET Collaboration team

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