Evans, DF, Southworth, J and Smalley, B (2016) WASP-20 IS A CLOSE VISUAL BINARY WITH A TRANSITING HOT JUPITER. Astrophysical Journal Letters, 833 (2). ISSN 2041-8213

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We announce the discovery that WASP-20 is a binary stellar system, consisting of two components separated by 0.2578 ± 0farcs0007 on the sky, with a flux ratio of 0.4639 ± 0.0015 in the K-band. It has previously been assumed that the system consists of a single F9 V star, with photometric and radial velocity signals consistent with a low-density transiting giant planet. With a projected separation of approximately 60 au between the two components, the detected planetary signals almost certainly originate from the brighter of the two stars. We reanalyze previous observations allowing for two scenarios, "planet transits A" and "planet transits B," finding that both cases remain consistent with a transiting gas giant. However, we rule out the "planet transits B" scenario because the observed transit duration requires star B to be significantly evolved, and therefore have an age much greater than star A. We outline further observations that can be used to confirm this finding. Our preferred "planet transits A" scenario results in the measured mass and radius of the planet increasing by 4σ and 1σ, respectively.

Item Type: Article
Additional Information: © 2016 IOP Publishing/American Astronomical Society. This is the final published version of the article (version of record). It first appeared online via IOP Publishing at http://dx.doi.org/10.3847/2041-8213/833/2/L19 - please refer to any applicable terms of use of the publisher.
Uncontrolled Keywords: binaries, visual, planets and satellites, detection, stars, individual (WASP-20), techniques, high angular resolution
Subjects: Q Science > QB Astronomy > QB460 Astrophysics
Divisions: Faculty of Natural Sciences > School of Chemical and Physical Sciences
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Depositing User: Symplectic
Date Deposited: 04 Apr 2017 09:25
Last Modified: 03 Apr 2019 10:59
URI: https://eprints.keele.ac.uk/id/eprint/3146

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