CCD Photometry of a Newly Confirmed SU UMa-Type Dwarf Nova, NSV 4838

TL;DR

This study presents detailed photometric observations of the dwarf nova NSV 4838, confirming its SU UMa-type classification, measuring superhump periods, estimating system parameters, and analyzing superhump period evolution and supercycle length.

Contribution

First detailed CCD photometry of NSV 4838 during outbursts, confirming its SU UMa-type nature and providing new measurements of superhump periods and system parameters.

Findings

Superhump periods of 0.0699 and 0.069824 days were measured.

The system's mass ratio was estimated as q=0.13.

Superhump period increased during the 2007 superoutburst.

Abstract

We present time-resolved CCD photometry of a dwarf nova NSV 4838 (UMa 8, SDSS J102320.27+440509.8) during the 2005 June and 2007 February outburst. Both light curves showed superhumps with a mean period of 0.0699(1) days for the 2005 outburst and 0.069824(83) days for the 2007 outburst, respectively. Using its known orbital period of 0.0678 days, we estimated the mass ratio of the system to be $q$=0.13 based on an empirical relation. Although the majority of SU UMa-type dwarf novae having similar superhump periods show negative period derivatives, we found that the superhump period increased at $\dot{P}$ / $P_{\rm sh}$=+7(+3, -4)$\times10^{-5}$ during the 2007 superoutburst. We also investigated long-term light curves of NSV 4838, from which we derived 340 days as a supercycle of this system.