CAOSP abstracts, Volume: 43, No.: 3, year: 2014

Abstract: We present the results of our study of a long and short-term variability of ER UMa. Obtained light curves revealed presence of superhumps during the whole supercycle. The superhumps period was not stable but varying from night to night. The O-C diagram suggests that both positive and negative superhumps were present. The form of the O-C digram is consistent with recently presented Kepler data of another SU UMa-type star — V1504 Cyg. We also examined data of about 20 years of observations of ER UMa from different databases. The O-C diagram for the moments of superoutbursts revealed a systematic change of the supercycle within 43.6 and 59.2 d. We associate these variations with the changes of a mass transfer rate.