Monitoring of FS Aurigae
Upon my request, during the 2010-2011 observing season, AAVSO observers have conducted continuous, nightly monitoring of the unique cataclysmic variable FS Aurigae to clearly define the start and end times of consecutive dwarf nova outbursts and measure their outburst properties. The campaign goals have been successfully met; we have observed 10 consecutive outbursts in great details. An active stage of the campaign is complete even though nightly monitoring of the star through the end of the observing season is encouraged. However, no new colour and/or time-resolved observations are needed anymore. Thank you very much to everyone who observed!
November 22, 2011: FS Aur is in quiescence but a new outburst is coming. I expect it in a few days.
FS Aur is an extremely unusual cataclysmic variable renown for the presence of a variety of uncommon and largely incomprehensible periodic variabilities of brightness and radial velocity. The outlandish peculiarity of FS Aur is the existence of a very coherent photometric period of 205.5 min that exceeds the spectroscopic orbital period of 85.7 minutes by 2.4 times. Such a discrepancy in the photometric and spectroscopic periods is highly unusual for cataclysmic variables.
Based on the short orbital period, FS Aur has been classified as a SU UMa star. Nevertheless, long‐term monitoring of the system by several groups failed to detect any superoutburst in its light curve. The publicly available AAVSO light curve show instead a steady‐cyclic outburst pattern that is more similar to a SS Cyg–type dwarf nova light curve. However, this monitoring reveals an additional, discordant, and very long photometric period of ~900 days. We explain the latter by the result of eccentricity modulation of a close binary orbit induced by the presence of a third body on a circumbinary orbit (Tovmassian et al., 2010).
Motivated by our recent discoveries, we are now attempting to better understand the outburst activity of FS Aur. FS Aur’s outbursts are very short (some 3 days), and only few outbursts were observed from the beginning to the end. The duration of an outburst cycle is highly variable and can be as short as 12-15 days. However, despite of almost fourteen hundred FS Aur observations obtained by the AAVSO observers largely after 1995, we have not found even one full coverage of the outburst cycle. We would be very interested to fill this gap.
If you are interested to participate in this project, you can find more information from AAVSO Alert Notice 428. I will provide on this page timely updates about the status of this work.