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Published February 11, 2015 | Published + Submitted + Supplemental Material
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High-precision photometry by telescope defocusing – VII. The ultrashort period planet WASP-103


We present 17 transit light curves of the ultrashort period planetary system WASP-103, a strong candidate for the detection of tidally-induced orbital decay. We use these to establish a high-precision reference epoch for transit timing studies. The time of the reference transit mid-point is now measured to an accuracy of 4.8 s, versus 67.4 s in the discovery paper, aiding future searches for orbital decay. With the help of published spectroscopic measurements and theoretical stellar models, we determine the physical properties of the system to high precision and present a detailed error budget for these calculations. The planet has a Roche lobe filling factor of 0.58, leading to a significant asphericity; we correct its measured mass and mean density for this phenomenon. A high-resolution Lucky Imaging observation shows no evidence for faint stars close enough to contaminate the point spread function of WASP-103. Our data were obtained in the Bessell RI and the SDSS griz passbands and yield a larger planet radius at bluer optical wavelengths, to a confidence level of 7.3σ. Interpreting this as an effect of Rayleigh scattering in the planetary atmosphere leads to a measurement of the planetary mass which is too small by a factor of 5, implying that Rayleigh scattering is not the main cause of the variation of radius with wavelength.

Additional Information

© 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2014 November 11. Received 2014 October 20. In original form 2014 September 2. First published online December 18, 2014. The operation of the Danish 1.54 m telescope is financed by a grant to UGJ from the Danish Natural Science Research Council (FNU). This paper incorporates observations collected using the Gamma Ray Burst Optical and Near-Infrared Detector (GROND) instrument at the MPG 2.2 m telescope located at ESO La Silla, Chile, program 093.A-9007(A). GROND was built by the high-energy group of MPE in collaboration with the LSW Tautenburg and ESO, and is operated as a PI-instrument at the MPG 2.2 m telescope. We thank Mike Gillon for helpful discussions. The reduced light curves presented in this work will be made available at the CDS (http://vizier.u-strasbg.fr/) and at http://www.astro.keele.ac.uk/∼jkt/. J Southworth acknowledges financial support from STFC in the form of an Advanced Fellowship. JB acknowledges funding by the Australian Research Council Discovery Project Grant DP120101792. Funding for the Stellar Astrophysics Centre is provided by The Danish National Research Foundation (grant agreement no. DNRF106). This supported by a Sapere Aude Starting Grant from The Danish Council for Independent Research. This publication was 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. CS received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 268421. OW (FNRS research fellow) and J Surdej acknowledge support from the Communauté francąise de Belgique – Actions de recherche concertées – Académie Wallonie-Europe. The following internet-based resources were used in research for this paper: the ESO Digitized Sky Survey; the NASA Astrophysics Data System; the SIMBAD data base and VizieR catalogue access tool operated at CDS, Strasbourg, France; and the arχiv scientific paper preprint service operated by Cornell University.

Attached Files

Submitted - 1411.2767v1.pdf

Published - MNRAS-2015-Southworth-711-21.pdf

Supplemental Material - alldata.zip

Supplemental Material - wasp103appendix.pdf


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August 20, 2023
August 20, 2023