Outburst of a WZ Sge-type dwarf nova, AL Com in 2007

TL;DR

This paper reports photometric observations of the 2007 outburst of the WZ Sge-type dwarf nova AL Com, highlighting unique rebrightening behavior and suggesting rebrightening types depend on the mass-accretion process rather than binary parameters.

Contribution

It provides detailed photometric analysis of AL Com's 2007 outburst, revealing rebrightening characteristics that differ from previous outbursts and proposing a new understanding of rebrightening mechanisms.

Findings

Rebrightening cycle of 1-2 days observed in 2007

Rebrightening characteristics differ from 1995 and 2001 outbursts

Rebrightening type depends on mass-accretion process, not binary parameters

Abstract

We report photometric observations of AL Com during its rare outburst in 2007. The light curve is reminiscent of its past superoutbursts in 1995 and 2001, except for the rebrightening phase after the main superoutburst. During the rebrightening phase in 2007, we found clear modulations between V=16.2-15.2. In conjunction with the lack of prominent superhumps in our time-series observations, the modulations can most naturally be interpreted as repetitive short rebrightenings with a cycle of 1-2 days. The rebrightening characteristics in 2007 are different from those in 1995 and 2001. This indicates that the type of rebrightenings in WZ Sge stars depends not on binary parameters of objects, but on the mass-accretion process for each outburst.