Kepler K2 and TESS Observations of Two Magnetic Cataclysmic Variables: The New Asynchronous Polar SDSS J084617.11+245344.1 and Paloma

Littlefield, Colin; Hoard, D.W.; Garnavich, Peter; Szkody, Paula; Mason, Paul A.; Scaringi, Simone; Ilkiewicz, Krystian; Kennedy, Mark R.; Rappaport, Saul A.; Jayaraman, Rahul

Abstract

There have been relatively few published long-duration, uninterrupted light curves of magnetic cataclysmic variable stars in which the accreting white dwarf's rotational frequency is slightly desynchronized from the binary orbital frequency. We report Kepler K2 and TESS observations of two such systems. The first, SDSS J084617.11+245344.1, was observed by the Kepler spacecraft for 80 days during Campaign 16 of the K2 mission, and we identify it as a new asynchronous polar with a likely 4.64 hr orbital period. This is significantly longer than any other asynchronous polar, as well as all but several synchronous polars. Its spin and orbital periods beat against each other to produce a conspicuous 6.77-day beat period, across which the system's accretion geometry gradually changes. The second system in this study, Paloma, was observed by TESS for one sector and was already known to be asynchronous. Until now, there had been an ambiguity in its spin period, but the TESS power spectrum pinpoints a spin period of 2.27 hr. During the resulting 0.7-day spin–orbit beat period, the light curve phased on the spin modulation alternates between being single and double humped. We explore two possible explanations for this behavior: the accretion flow being diverted from one of the poles for part of the beat cycle, or an eclipse of the emitting region responsible for the second hump.

Citation

Littlefield, C., Hoard, D., Garnavich, P., Szkody, P., Mason, P. A., Scaringi, S., …Jayaraman, R. (2023). Kepler K2 and TESS Observations of Two Magnetic Cataclysmic Variables: The New Asynchronous Polar SDSS J084617.11+245344.1 and Paloma. Astronomical Journal, 165(2), Article 43. https://doi.org/10.3847/1538-3881/aca1a5

• Journal Article Type: Article
• Acceptance Date: Nov 7, 2022
• Online Publication Date: Jan 9, 2023
• Publication Date: 2023
• Deposit Date: Jun 8, 2023
• Publicly Available Date: Jun 8, 2023
• Journal: The Astronomical Journal
• Print ISSN: 0004-6256
• Electronic ISSN: 1538-3881
• Publisher: IOP Publishing
• Peer Reviewed: Peer Reviewed
• Volume: 165
• Issue: 2
• Article Number: 43
• DOI: https://doi.org/10.3847/1538-3881/aca1a5
• Public URL: https://durham-repository.worktribe.com/output/1170475