[vsnet-alert 7593] CU Vel: superoutburst update, superhump period

[Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>]

CU Vel: superoutburst update, superhump period

Dear Colleagues,

   We have received further data from Greg Bolt.  On December 14, the
superhumps have fully grown with an amplitude of 0.25 mag.  Prominent
super-QPO-type signal on Dec. 11 looks like to have disappeared.

   From the available observations, we have determined a preliminary
superhump period of 0.07927(2) d, which is significantly shorter than
the perviously adopted value.  However, this period is only 1% larger
than the adopted orbital period (0.0785 d).  Such a small superhump period
excess is very rare among long-period (long-Psh) systems, but is more
common in WZ Sge-type stars.  This possible small period excess may be
a result of a small mass-ratio (q=0.12, Mennickent and Diaz (1996) A&A,
309, 147).  Otherwise, it may be also possible that the superhump period
may have not been stabilized yet.

   Both the discrepancy from the past observation and the possiblly
unusually low superhump period excess strongly encourage us to further
observe the present CU Vel superoutburst in detail throughout the
course of the superoutburst.  We may even expect that some features
similar to those of WZ Sge stars can appear.  As long as the object
is observable, please make as long observations possible (hopefully
more than 3 hours per night)!  The object is currently the top-priority
southern target.

Regards,
Taichi Kato
VSNET Collaboration team

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