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Larger and faster: revised properties and a shorter orbital period for the WASP-57 planetary system from a pro-am collaboration

Southworth, John; Mancini, L.; Tregloan-Reed, J.; Calchi Novati, S.; Ciceri, S.; D'Ago, G.; Delrez, L.; Dominik, M.; Evans, D. F.; Gillon, M.; Jehin, E.; Jørgensen, U. G.; Haugbølle, T.; Lendl, M.; Arena, C.; Barbieri, L.; Barbieri, M.; Corfini, G.; Lopresti, C.; Marchini, A.; Marino, G.; Alsubai, K. A.; Bozza, V.; Bramich, D. M.; Jaimes, R. Figuera; Hinse, T. C.; Henning, Th.; Hundertmark, M.; Juncher, D.; Korhonen, H.; Popovas, A.; Rabus, M.; Rahvar, S.; Schmidt, R. W.; Skottfelt, J.; Snodgrass, C.; Starkey, D.; Surdej, J. and Wertz, O. (2015). Larger and faster: revised properties and a shorter orbital period for the WASP-57 planetary system from a pro-am collaboration. Monthly Notices of the Royal Astronomical Society, 454(3) pp. 3094–3107.

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Transits in the WASP-57 planetary system have been found to occur half an hour earlier than expected. We present 10 transit light curves from amateur telescopes, on which this discovery was based, 13 transit light curves from professional facilities which confirm and refine this finding, and high-resolution imaging which show no evidence for nearby companions. We use these data to determine a new and precise orbital ephemeris, and measure the physical properties of the system. Our revised orbital period is 4.5 s shorter than found from the discovery data alone, which explains the early occurrence of the transits. We also find both the star and planet to be larger and less massive than previously thought. The measured mass and radius of the planet are now consistent with theoretical models of gas giants containing no heavy-element core, as expected for the subsolar metallicity of the host star. Two transits were observed simultaneously in four passbands. We use the resulting light curves to measure the planet's radius as a function of wavelength, finding that our data are sufficient in principle but not in practise to constrain its atmospheric properties. We conclude with a discussion of the current and future status of transmission photometry studies for probing the atmospheres of gas-giant transiting planets.

Item Type: Journal Item
Copyright Holders: 2015 The Authors
ISSN: 1365-2966
Project Funding Details:
Funded Project NameProject IDFunding Body
GrantFRFC 2.5.594.09.FBelgian Fund for Scientific Research with the participation of the SNF (Swiss National Science Fundation)
GrantNPRP X-019-1- 006Qatar National Research Fund
Keywords: stars; fundamental parameters; WASP-57; planetary systems
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Research Group: Centre for Electronic Imaging (CEI)
Item ID: 44750
Depositing User: Colin Snodgrass
Date Deposited: 03 Nov 2015 10:27
Last Modified: 07 Dec 2018 10:36
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