The 2006 November outburst of EG Aquarii: the SU UMa nature revealed

TL;DR

This study presents detailed photometric observations of EG Aquarii during its 2006 outburst, revealing superhumps and confirming its classification as an SU UMa-type dwarf nova, with insights into its period behavior and long-term activity.

Contribution

The paper provides the first clear detection of superhumps during a precursor in EG Aquarii and discusses its long-term inactivity despite typical SU UMa features.

Findings

Superhumps with a period of 0.078828 days were detected during the outburst.

An abrupt superhump period shift occurred near the outburst maximum.

EG Aquarii shows no outbursts over a decade, indicating long-term inactivity.

Abstract

We report time-resolved CCD photometry of the cataclysmic variable EG Aquarii during the 2006 November outburst During the outburst, superhumps were unambiguously detected with a mean period of 0.078828(6) days, firstly classifying the object as an SU UMa-type dwarf nova. It also turned out that the outburst contained a precursor. At the end of the precursor, immature profiles of humps were observed. By a phase analysis of these humps, we interpreted the features as superhumps. This is the second example that the superhumps were shown during a precursor. Near the maximum stage of the outburst, we discovered an abrupt shift of the superhump period by ${\sim}$ 0.002 days. After the supermaximum, the superhump period decreased at the rate of $\dot{P}/P$=$-8.2{\times}10^{-5}$, which is typical for SU UMa-type dwarf novae. Although the outburst light curve was characteristic of SU UMa-type dwarf novae, long-term monitoring of the variable shows no outbursts over the past decade. We note on the basic properties of long period and inactive SU UMa-type dwarf novae.