A window on exoplanet dynamical histories: Rossiter–McLaughlin observations of WASP-13b and WASP-32b
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 (λ). WASP-13b and WASP-32b both have prograde orbits and are consistent with alignment with measured sky-projected angles...
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Published in | Monthly notices of the Royal Astronomical Society Vol. 440; no. 4; pp. 3392 - 3401 |
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Main Authors | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
Format | Journal Article Web Resource |
Language | English |
Published |
London
Oxford University Press
01.06.2014
Oxford University Press (OUP): Policy P - Oxford Open Option A Blackwell Publishing |
Subjects | |
Online Access | Get full text |
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Summary: | 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 (λ). WASP-13b and WASP-32b both have prograde orbits and are consistent with alignment with measured sky-projected angles of $\lambda =8{^{\circ }}^{+13}_{-12}$ and $\lambda =-2{^{\circ }}^{+17}_{-19}$, respectively. Both WASP-13 and WASP-32 have T
eff < 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 P
rot = 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
* = 90° 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 = 11° ± 14°. We conclude with a discussion on the alignment of systems around cool host stars with T
eff < 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. |
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Bibliography: | scopus-id:2-s2.0-84899870032 |
ISSN: | 0035-8711 1365-2966 1365-2966 |
DOI: | 10.1093/mnras/stu520 |