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Testing the planetary models of HU Aquarii

Bours, MCP, Marsh, TR, Breedt, E, Copperwheat, CM, Dhillon, VS, Leckngam, A, Littlefair, SP, Parsons, SG and Prasit, A (2014) Testing the planetary models of HU Aquarii. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 445 (2). pp. 1924-1931. ISSN 0035-8711

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We present new eclipse observations of the polar (i.e. semidetached magnetic white dwarf + M-dwarf binary) HU Aqr, and mid-egress times for each eclipse, which continue to be observed increasingly early. Recent eclipses occurred more than 70 s earlier than the prediction from the latest model that invoked a single circumbinary planet to explain the observed orbital period variations, thereby conclusively proving this model to be incorrect. Using ULTRACAM data, we show that mid-egress times determined for simultaneous data taken at different wavelengths agree with each other. The large variations in the observed eclipse times cannot be explained by planetary models containing up to three planets, because of poor fits to the data as well as orbital instability on short time-scales. The peak-to-peak amplitude of the O−C diagram of almost 140 s is also too great to be caused by Applegate's mechanism, movement of the accretion spot on the surface of the white dwarf, or by asynchronous rotation of the white dwarf. What does cause the observed eclipse time variations remains a mystery.

Item Type: Article
Additional Information: This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record M. C. P. Bours, T. R. Marsh, E. Breedt, C. M. Copperwheat, V. S. Dhillon, A. Leckngam, S. P. Littlefair, S. G. Parsons, A. Prasit, Testing the planetary models of HU Aquarii, Monthly Notices of the Royal Astronomical Society, Volume 445, Issue 2, 01 December 2014, Pages 1924–1931, is available online at:https://doi.org/10.1093/mnras/stu1879
Uncontrolled Keywords: 0201 Astronomical and Space Sciences
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
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Date Deposited: 25 Jul 2019 13:13
Last Modified: 04 Sep 2021 09:09
DOI or ID number: 10.1093/mnras/stu1879
URI: https://researchonline.ljmu.ac.uk/id/eprint/11040
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