NY Serpentis: SU UMa-Type Nova in the Period Gap with Diversity of Normal Outbursts

TL;DR

This study of NY Ser, an SU UMa-type nova in the period gap, reveals diverse normal outburst behaviors and detailed superhump and orbital period characteristics through photometric observations in 2002 and 2013.

Contribution

It provides the first detailed analysis of NY Ser's outburst diversity and superhump behavior, highlighting its unique activity states within the period gap.

Findings

NY Ser exhibits two distinct activity states with different outburst frequencies.

A wide ~12-day normal outburst was observed without superhumps, dominated by orbital modulation.

Frequent outbursts showed positive superhumps co-existing with orbital modulation.

Abstract

We present photometric study of NY Ser, an in-the-gap SU UMa-type nova, in 2002 and 2013. We determined the duration of the superoutburst and the mean superhump period to be 18 d and 0.10458 d, respectively. We detected in 2013 that NY Ser showed two distinct states separated by the superoutburst. A state of rather infrequent normal outbursts lasted at least 44 d before the superoutburst and a state of frequent outbursts started immediately after the superoutburst and lasted at least for 34 d. Unlike a typical SU UMa star with bimodal distribution of the outbursts duration, NY Ser displayed a diversity of normal outbursts. In the state of infrequent outbursts, we detected a wide ~12 d outburst accompanied by 0.098 d orbital modulation but without superhumps ever established in NY Ser. We classified this as the "wide normal outburst". The orbital period dominated both in quiescence and during normal outbursts in this state. In the state of the most frequent normal outbursts, the 0.10465 d positive superhumps dominated and co-existed with the orbital modulation. In 2002 we detected the normal outburst of "intermediate" 5-6 d duration that was also accompanied by orbital modulations.