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Observation and Modelling of Transits and Starspots in the WASP-19 Planetary System

Published online by Cambridge University Press:  29 April 2014

Jeremy Tregloan-Reed  and
John Southworth
Jeremy Tregloan-Reed
Affiliation:
Keele University, Staffordshire, ST5 5BG, U.K email: j.j.tregloan-reed@keele.ac.uk
John Southworth
Affiliation:
Keele University, Staffordshire, ST5 5BG, U.K email: j.j.tregloan-reed@keele.ac.uk
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Abstract

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We have developed a new model for analysing light curves of planetary transits when there are starspots on the stellar disc. Because the parameter space contains a profusion of local minima we developed a new optimisation algorithm which combines the global minimisation power of a genetic algorithm and the Bayesian statistical analysis of the Markov chain. With these tools we modelled three transit light curves of WASP-19. Two light curves were obtained on consecutive nights and contain anomalies which we confirm as being due to the same spot. Using these data we measure the star's rotation period and velocity to be 11.76 ± 0.09 d and 3.88 ± 0.15 kms−1, respectively, at a latitude of 65°. We find that the sky-projected angle between the stellar spin axis and the planetary orbital axis is λ = 1.0° ± 1.2°, indicating axial alignment. Our results are consistent with and more precise than published spectroscopic measurements of the Rossiter-McLaughlin effect.

Keywords

stars: planetary systemsstars: spotsstars: rotationstars: individual (WASP-19)
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 8 , Symposium S293: Formation, Detection, and Characterization of Extrasolar Habitable Planets , August 2012 , pp. 116 - 118
Copyright
Copyright © International Astronomical Union 2014 

References

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