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GO Com: superhump period increase! (beat phenomenon?) Dear Colleagues, We have received new data from Nakajima-san, Tonny Vanmunster (2 nights), Brian Martin, Tom Krajci, and Tanabe-san (VSNET Okayama station) and the OUS team. Surprisingly, the superhump period of GO Com increased during the past one night! Such a sudden change in the superhump period is rarely seen during the superoutburst plateau stage. The period change may be alternately interpreted as the effect of a "beat phenomenon" between the superhump period and orbital period (the best example in an non-eclipsing SU UMa/WZ Sge star being RZ Leo: Ishioka et al. 2001 PASJ 53, 905, see also http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/DNe/rzleo.html ). One may remember the strong effect of beat phenomenon during the 2001 superoutburst of WZ Sge, see http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/DNe/wzsge01.html ). There is also a hint of beat phenomenon in the mean magnitude and the superhump amplitude. If the second interpretation is correct, the estimated fractional superhump excess is about 2.5%, which is not unusual for an SU UMa-type dwarf nova with this superhump period. In any case, the superhump evolution of GO Com has not been monotonous. We therefore strongly encourage observations as continously and thoroughly as possible during the entire superoutburst and the subsequent post-superoutburst stage! Regards, Taichi Kato VSNET Collaboration team
Return to the Daisaku Nogami
vsnet-adm@kusastro.kyoto-u.ac.jp
