REVISITING FS AURIGAE AND ITS TRIPLE CATACLYSMIC VARIABLE SYSTEM HYPOTHESIS

Abstract

A very long term variability (VLPP), with period of 875 days, was observed in the long-term light curve of FS Aurigae (FS Aur) in 2011. This periodicity was calculated over 6 cycles. We re-examined the periodicity with new observations over the past 5 yrs. A total of 18 years of observations confirm the hypothesis of a third body perturbing in a secular way the cataclysmic variable (CV). Improvements to the model such as eccentric and inclined orbits for the third body and a binary post-Newtonian correction are considered. We confirm the VLPP of FS Aur and find the new period of 857 ± 78 days. The secular perturbations are most efficient when the mass of the third body is M₃≈ 29MJ, much less than the 50MJ reported in 2011. We estimate the effect of the third body on the mass transfer rate and on the brightness of the system. We consider alternative scenarios for the VLPP. New data and analysis support the hypothesis that FS Aur is a CV in a triple system.