Dwarf Novae in the Shortest Orbital Period Regime: I. A New Short Period Dwarf Nova, OT J055717+683226

TL;DR

This paper reports the discovery and analysis of a new short-period dwarf nova, OT J055717+683226, revealing its superoutburst behavior, supercycle length, and classification within the shortest orbital period dwarf novae.

Contribution

It introduces a newly observed dwarf nova with a very short superhump period and classifies it within a specific subgroup using hierarchical cluster analysis.

Findings

Superhump period of 76.67 minutes for OT J055717+683226

Supercycle length estimated at approximately 480 days

Identification of a subgroup with short supercycles and large superhump period excesses

Abstract

We report the observation of a new dwarf nova, OT J055717+683226, during its first-ever recorded superoutburst in December 2006. Our observation shows that this object is an SU UMa-type dwarf nova having a very short superhump period of 76.67+/- 0.03 min (0.05324+/-0.00002 d). The next superoutburst was observed in March 2008. The recurrence time of superoutbursts (supercycle) is, hence, estimated to be ~480 d. The supercycle is much shorter than those of WZ Sge-type dwarf novae having supercycles of >~ 10 yr, which are a major population of dwarf novae in the shortest orbital period regime (<~85 min). Using a hierarchical cluster analysis, we identified seven groups of dwarf novae in the shortest orbital period regime. We identified a small group of objects that have short supercycles, small outburst amplitudes, and large superhump period excesses, compared with those of WZ Sge stars. OT J055717+683226 probably belongs to this group.