A window on exoplanet dynamical histories: Rossiter-McLaughlin observations of WASP-13b and WASP-32b

作者：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 Gomez Maqueo; Cameron A Collier; 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; Maxted P F L; McCormac J; Miller G R M

来源：Monthly Notices of the Royal Astronomical Society, 2014, 440(4): 3392-3401.

DOI：10.1093/mnras/stu520

• techniques: photometric
• techniques: radial velocities
• stars: individual: WASP-13
• stars: individual: WASP-32
• planetary systems

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 lambda = 8 degrees(+13)(-12) and lambda = -2 degrees(+17)(-19), respectively. Both WASP-13 and WASP-32 have T-eff %26lt; 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 nu sin i if a stellar inclination of i(*) = 90 degrees is assumed. With the determined rotation period, the true 3D angle between the stellar rotation axis and the planetary orbit, psi, was found to be psi = 11 degrees +/- 14 degrees. We conclude with a discussion on the alignment of systems around cool host stars with T-eff %26lt; 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.

• 出版日期2014-6