SDSS J162718.39+120435.0 - a dwarf nova in the period gap

TL;DR

This paper reports the first real-time observation of an outburst in the dwarf nova SDSS J162718.39+120435.0, confirming its classification as an SU UMa type and analyzing its superhump and orbital periods within the period gap.

Contribution

It provides the first real-time photometric data of an outburst in this dwarf nova and refines its superhump and orbital periods, situating it within the period gap of cataclysmic variables.

Findings

Detected superhumps confirming SU UMa classification

Measured superhump period change during outburst

Estimated orbital period within the period gap

Abstract

SDSS J162718.39+120435.0 was suspected of being a dwarf nova from spectroscopic observations made available by the Sloan Digital Sky Survey. Photometry conducted during the 2008 outburst, the first ever outburst of this object detected and followed up in real time, shows that the outburst reached magnitude 14.6 at maximum, had an amplitude of 4.6 magnitudes and lasted for at least 18 days. Common superhumps were detected with an amplitude of up to 0.4 magnitudes, confirming it to be a member of the SU UMa family. Initially the superhump period, Psh, was 0.10993(7) days (2.638 hours), but it subsequently reduced to Psh = 0.10890(9) days (2.614 hours) later in the outburst. The period change corresponds to the end of the plateau period of the outburst. The orbital period, Porb, was estimated from the two Psh values as between 0.1026 d and 0.1016 d, which places SDSS1627 near the centre of the period gap in the orbital period distribution of cataclysmic variables.