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Hitting a New Low: The Unique 28 hr Cessation of Accretion in the TESS Light Curve of YY Dra (DO Dra)

Hill, Katherine L.; Littlefield, Colin; Garnavich, Peter; Scaringi, Simone; Szkody, Paula; Mason, Paul A.; Kennedy, Mark R.; Shaw, Aarran W.; Covington, Ava E.

Hitting a New Low: The Unique 28 hr Cessation of Accretion in the TESS Light Curve of YY Dra (DO Dra) Thumbnail


Authors

Katherine L. Hill

Colin Littlefield

Peter Garnavich

Paula Szkody

Paul A. Mason

Mark R. Kennedy

Aarran W. Shaw

Ava E. Covington



Abstract

We present the Transiting Exoplanet Surveying Satellite light curve of the intermediate polar YY Draconis (YY Dra, also known as DO Dra). The power spectrum indicates that while there is stream-fed accretion for most of the observational period, there is a day-long, flat-bottomed low state at the beginning of 2020 during which the only periodic signal is ellipsoidal variation and there is no appreciable flickering. We interpret this low state to be a complete cessation of accretion, a phenomenon that has been observed only once before in an intermediate polar. Simultaneous ground-based observations of this faint state establish that when accretion is negligible, YY Dra fades to g = 17.37 ± 0.12, which we infer to be the magnitude of the combined photospheric contributions of the white dwarf and its red dwarf companion. Using survey photometry, we identify additional low states in 2018–2019 during which YY Dra repeatedly fades to—but never below—this threshold. This implies relatively frequent cessations in accretion. Spectroscopic observations during future episodes of negligible accretion can be used to directly measure the field strength of the white dwarf by Zeeman splitting. Separately, we search newly available catalogs of variable stars in an attempt to resolve the long-standing dispute over the proper identifier of this system.

Citation

Hill, K. L., Littlefield, C., Garnavich, P., Scaringi, S., Szkody, P., Mason, P. A., …Covington, A. E. (2022). Hitting a New Low: The Unique 28 hr Cessation of Accretion in the TESS Light Curve of YY Dra (DO Dra). Astronomical Journal, 163(6), Article 246. https://doi.org/10.3847/1538-3881/ac5a51

Journal Article Type Article
Acceptance Date Mar 1, 2022
Online Publication Date May 3, 2022
Publication Date Jun 1, 2022
Deposit Date Jul 14, 2022
Publicly Available Date Mar 29, 2024
Journal The Astronomical Journal
Print ISSN 0004-6256
Electronic ISSN 1538-3881
Publisher IOP Publishing
Peer Reviewed Peer Reviewed
Volume 163
Issue 6
Article Number 246
DOI https://doi.org/10.3847/1538-3881/ac5a51

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http://creativecommons.org/licenses/by/4.0/

Copyright Statement
Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.





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