[vsnet-alert 10320] VY Aqr: new stage of outburst evolution

Taichi Kato tkato at kusastro.kyoto-u.ac.jp
Sat Jul 12 13:31:06 JST 2008

VY Aqr: new stage of outburst evolution

   We have received further data from the OUS team, Berto Monard, Itoh-san
and Kyoto team.

   These data indicate a period increase between July 2.5 and July 10.5.
The mean Pdot/P during this interval was +9.6(5)*10^(-5).
Since July 10.5, the period started to decrease, accompanied
by a flattening of the global decline and regrowth of superhumps.
A similar trend has been recorded several systems with relatively
rere superoutbursts (cf. PASJ 55, 989).  The period decrease and
the growth of superhumps may be attributed to a growth of a new
component of superhumps.

   These results suggest that the current plateau stage will terminate
within a few days, accompanied by a rapid decline.  Further rebrightening(s)
are expected, since VY Aqr is one of the renowned objects for the
rebrightening phenomenon (cf. Richter, 1992ASPC...29...12R).

   Please continue the present time-series coverage even after the
rapid decline and potential rebrightening(s), since the detection
of "late superhumps" can be crucial in clarifying the mechanism of
the superoutburst (cf. arXiv:0806.4248).

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