Three new cataclysmic variables from SDSS: are they short period systems?

Abstract

There exist white dwarfs, the remnants of burned-out stars, which accrete material from non degenerate stars that are helium-rich, known as AM CVn stars. These systems are strong sources of gravitational wave radiation and will serve as crucial calibrators for the upcoming LISA mis sion. Despite their importance, their formation remains unclear. One proposed formation channel suggests they evolve from systems known as cataclysmic variables, in which a white dwarf accretes material from a companion star, which at some point, the external hydrogen layers are depleted, revealing the underlying helium-rich layer. In this study, I have identified three systems displaying strong helium lines in addition to hydrogen. Therefore, these systems could potentially be transitioning from cataclysmic variables to AMCVntype. Acrucialparametertoconfirmthis transition is the orbital period, as cataclysmic variables reach a minimum period of 70 minutes. Analyzing photometric data from three telescopes: the Zwicky Transient Facility (ZTF) survey, the Transiting Exoplanet Survey Satellite (TESS) satellite mission, and the mexican telescope MEXCAM. I was able to measure a periodicity for one of these systems. Although the period was not robustly identified in one dataset, it was consistently present in all three datasets. I conclude that this periodicity is likely the orbital period, considering the characteristics of the system. Furthermore, this system could represent another potential candidate progenitor of AM CVn through the cataclysmic variable formation channel