[vsnet-alert 11203] IY UMa superhump evolution

[Taichi Kato]

IY UMa superhump evolution

   We have reported observations from Okayama U. of Sci. team , Nakajima-san,
Mike Simonsen and Arto Oksanen.  The object showed a long superhump period
before Apr. 21 (mean Psh = 0.07626(2) d and Pdot = +2*10^(-5)).  The period
then experienced a transition to a shorter one (mean Psh = 0.07565(8) d).
Although past observations of IY UMa had not clearly shown this kind of
period evolution, the current observation seems to establish the presence
of a segment with a positive period derivative.  The long duration of
this segment as well as a long superhump period appear to strengthen the
similarity with NSV 4838 (Imada et al. PASJ in press, arXiv:0902.1013).