Transits and starspots in the WASP-6 planetary system
- Creators
- Tregloan-Reed, Jeremy
- Calchi Novati, S.
Abstract
We present updates to prism, a photometric transit-starspot model, and gemc, a hybrid optimization code combining MCMC and a genetic algorithm. We then present high-precision photometry of four transits in the WASP-6 planetary system, two of which contain a starspot anomaly. All four transits were modelled using prism and gemc, and the physical properties of the system calculated. We find the mass and radius of the host star to be 0.836 ± 0.063 M_⊙ and 0.864 ± 0.024 R_⊙, respectively. For the planet, we find a mass of 0.485 ± 0.027 MJup, a radius of 1.230 ± 0.035 R_(Jup) and a density of 0.244 ± 0.014 ρ_(Jup). These values are consistent with those found in the literature. In the likely hypothesis that the two spot anomalies are caused by the same starspot or starspot complex, we measure the stars rotation period and velocity to be 23.80 ± 0.15 d and 1.78 ± 0.20 km s^(−1), respectively, at a colatitude of 75.8°. We find that the sky-projected angle between the stellar spin axis and the planetary orbital axis is λ = 7.2° ± 3.7°, indicating axial alignment. Our results are consistent with and more precise than published spectroscopic measurements of the Rossiter–McLaughlin effect. These results suggest that WASP-6 b formed at a much greater distance from its host star and suffered orbital decay through tidal interactions with the protoplanetary disc.
Additional Information
© 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2015 March 30. Received 2015 March 27. In original form 2014 February 20. First published online April 28, 2015. We like to thank the anonymous referee for the helpful comments on the manuscript. The operation of the Danish 1.54-m telescope at ESOs La Silla observatory is financed by a grant to UGJ from The Danish Council for Independent Research (FNU). Research at the Armagh Observatory is funded by the Department of Culture, Arts & Leisure (DCAL). JTR acknowledges financial support from STFC in the form of a PhD Studentship (the majority of this work) and also acknowledges financial support from ORAU (Oak Ridge Associated Universities) and NASA in the form of a Post-Doctoral Programme (NPP) Fellowship. JS acknowledges financial support from STFC in the form of an Advanced Fellowship. DR acknowledges financial support from the Spanish Ministry of Economy and Competitiveness (MINECO) under the 2011 Severo Ochoa Programme MINECO SEV-2011-0187. FF, DR (boursier FRIA) and J Surdej acknowledge support from the Communauté française de Belgique – Actions de recherche concertées – Académie Wallonie–Europe.Attached Files
Published - MNRAS-2015-Tregloan-Reed-1760-9.pdf
Submitted - 1503.09184v1.pdf
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Additional details
- Eprint ID
- 58854
- Resolver ID
- CaltechAUTHORS:20150710-144313752
- Danish Council for Independent Research (FNU)
- Department of Culture, Arts Leisure (DCAL)
- Science and Technology Facilities Council (STFC)
- Oak Ridge Associated Universities (ORAU)
- NASA Postdoctoral Program
- Ministerio de Economía y Competitividad (MINECO)
- SEV-2011-0187
- Severo Ochoa
- Communauté française de Belgique – Actions de recherche concertées – Académie universitaire Wallonie-Europe
- Created
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2015-07-10Created from EPrint's datestamp field
- Updated
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2021-11-10Created from EPrint's last_modified field