Outburst Behaviour of the Dwarf Nova CG Draconis

TL;DR

This study presents extensive photometric observations of dwarf nova CG Draconis, revealing two types of outbursts and providing updated orbital parameters, suggesting it may be a transitional subtype or challenge existing superoutburst models.

Contribution

It offers the first comprehensive dataset and analysis of CG Draconis's outburst behavior, orbital period, and eclipse profiles, proposing a possible new intermediary dwarf nova subtype.

Findings

Identified two types of quasi-periodic outbursts with distinct amplitudes.

Found an orbital period of approximately 4 hours 31 minutes.

No superhumps were detected during outbursts.

Abstract

During the British Astronomical Association (BAA) 2022 campaign, 27436 photometric observations of the dwarf nova (DN) CG Draconis were made, with 106 eclipses recorded. This work summarizes the new data available and provides updated ephemeris and commentary on the observed eclipse profiles. The orbital period found is P_orb = 4h31m38s +/- 1s. Two types of quasi-periodic outbursts are identified: normal outbursts, of Delta V of approximately 1.25 mag amplitude, and bright, of Delta V of approximately 1.5 mag. The pattern resembles superoutbursts of SU UMa-type DNe, however, no presence of superhumps characterizing these DNe was found. Given CG Dra is located above the period gap, it may represent a new intermediary subtype between SS Cyg and SU UMa-type stars, or provide support to superoutburst models that do not rely on eccentric accretion disks.