A window on exoplanet dynamical histories : Rossiter-McLaughlin observations of WASP-13b and WASP-32b
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Date
01/06/2014Author
Grant ID
ST/J001651/1
PP/F000065/1
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We present Rossiter-McLaughlin observations of WASP-13b and WASP-32b and determine the sky-projected angle between the normal of the planetary orbit and the stellar rotation axis (lambda). WASP-13b and WASP-32b both have prograde orbits and are consistent with alignment with measured sky-projected angles of λ = 8º+13-12 and λ = -2º+17-19, respectively. Both WASP-13 and WASP-32 have Teff <6250 K, and therefore, these systems support the general trend that aligned planetary systems are preferentially found orbiting cool host stars. A Lomb-Scargle periodogram analysis was carried out on archival SuperWASP data for both systems. A statistically significant stellar rotation period detection (above 99.9 per cent confidence) was identified for the WASP-32 system with Prot = 11.6 ± 1.0 days. This rotation period is in agreement with the predicted stellar rotation period calculated from the stellar radius, R*, and vsin i if a stellar inclination of i* = 90º is assumed. With the determined rotation period, the true 3D angle between the stellar rotation axis and the planetary orbit, ψ, was found to be ψ = 11º ± 14º. We conclude with a discussion on the alignment of systems around cool host stars with Teff <6150 K by calculating the tidal dissipation time-scale. We find that systems with short tidal dissipation time-scales are preferentially aligned and systems with long tidal dissipation time-scales have a broad range of obliquities.
Citation
Brothwell , R D , Watson , C A , Hebrard , G , Triaud , A H M J , Cegla , H M , Santerne , A , Hebrard , E , Anderson , D R , Pollacco , D , Simpson , E K , Bouchy , F , Brown , D J A , Chew , Y G M , Cameron , A C , Armstrong , D J , Barros , S C C , Bento , J , Bochinski , J , Burwitz , V , Busuttil , R , Delrez , L , Doyle , A P , Faedi , F , Fumel , A , Gillon , M , Haswell , C A , Hellier , C , Jehin , E , Kolb , U , Lendl , M , Liebig , C E , Maxted , P F L , McCormac , J , Miller , G , Norton , A J , Pepe , F , Queloz , D , Rodriguez , J , Segransan , D , Skillen , I , Smalley , B , Stassun , K G , Udry , S , West , R G & Wheatley , P J 2014 , ' A window on exoplanet dynamical histories : Rossiter-McLaughlin observations of WASP-13b and WASP-32b ' , Monthly Notices of the Royal Astronomical Society , vol. 440 , no. 4 , pp. 3392-3401 . https://doi.org/10.1093/mnras/stu520
Publication
Monthly Notices of the Royal Astronomical Society
Status
Peer reviewed
ISSN
0035-8711Type
Journal article
Description
RDB acknowledges support from the Queen's University Belfast Department for Education and Learning (DEL) university scholarship. CAW acknowledges support by STFC grant ST/I001123/1. A. H. M. J. Triaud is Swiss National Science Foundation fellow under grant number PBGEP2-145594. AS acknowledges the support from the European Research Council/European Community under the FP7 through Starting Grant agreement number 239953.Collections
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