Larger and faster : revised properties and a shorter orbital period for the WASP-57 planetary system from a pro-am collaboration
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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.
Southworth , J , 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 , Figuera Jaimes , R J , Hinse , T C , Henning , T , Hundertmark , M , Juncher , D , Korhonen , H , Popovas , A , Rabus , M , Rahvar , S , Schmidt , R W , Skottfelt , J , Snodgrass , C , Starkey , D , Surdej , J & 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 , vol 454 , no. 3 , pp. 3094-3107 . DOI: 10.1093/mnras/stv2183
Monthly Notices of the Royal Astronomical Society
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
MG and EJ are FNRS Research Associates. LD is a FNRS/FRIA Doctoral Fellow. J Southworth acknowledges financial support from STFC in the form of an Advanced Fellowship. This publication was partially supported by grant NPRP X-019-1-006 from Qatar National Research Fund (a member of Qatar Foundation). TCH is supported by the Korea Astronomy & Space Science Institute travel grant #2014-1-400-06. TCH acknowledges support from the Korea Astronomy and Space Science Institute (KASI) grant 2014-1-400-06. OW (FNRS research fellow) and J Surdej acknowledge support from the Communauté française de Belgique – Actions de recherche concertées – Académie Wallonie-Europe.
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