Quiescent photometric modulations of two low-inclination cataclysmic variables KZGem and TWVir

TL;DR

This study analyzes quiescent photometric modulations of two low-inclination cataclysmic variables, KZ Gem and TW Vir, using Kepler K2 data, revealing updated orbital periods and insights into their light curve stability and disk behavior.

Contribution

The paper introduces a phase-correcting method to accurately determine orbital periods and analyzes light curve morphologies, providing new classifications and stability assessments of KZ Gem and TW Vir.

Findings

KZ Gem has an orbital period of 0.22242 days, classifying it as a long-period CV.

TW Vir's orbital period is refined to 0.182682 days.

KZ Gem shows stable orbital modulations, while TW Vir exhibits variable modulations.

Abstract

The quiescent periodic photometric modulations of two low-inclination cataclysmic variables observed in Kepler K2 Campaigns 0 and 1, KZ Gem and TW Vir, are investigated. A phase-correcting method was successfully used to detect the orbital modulations of KZ Gem and TW Vir and improve their orbital periods. The light curve morphologies of both CVs were further analyzed by defining flux ratios and creating colormaps. KZ Gem shows ellipsoidal modulations with an orbital period of 0.22242(1) day, twice the period listed in the updated RK catalogue (Edition 7.24). With this newly determined period, KZ Gem is no longer a CV in the period gap, but a long-period CV. A part of the quiescent light curve of TW Vir that had the highest stability was used to deduce its improved orbital period of 0.182682(3) day. The flat patterns shown in the colormaps of the flux ratios for KZ Gem demonstrate the stability of their orbital modulations, while TW Vir show variable orbital modulations during the K2 datasets. In TW Vir, the single versus double-peaked nature of the quiescent orbital variations before and after superoutburst may be related to the effect of the superoutburst on the accretion disk.