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

R. D. Brothwell*, C. A. Watson, G. Hebrard, A. H. M. J. Triaud, H. M. Cegla, A. Santerne, E. Hebrard, D. R. Anderson, D. Pollacco, E. K. Simpson, F. Bouchy, David John Alexander Brown, Y. Gomez Maqueo Chew, Andrew Collier Cameron, D. J. Armstrong, S. C. C. Barros, J. Bento, J. Bochinski, V. Burwitz, R. BusuttilL. Delrez, A. P. Doyle, F. Faedi, A. Fumel, M. Gillon, C. A. Haswell, C. Hellier, E. Jehin, U. Kolb, M. Lendl, Christine Elisabeth Liebig, P. F. L. Maxted, J. McCormac, Grant Miller, A. J. Norton, F. Pepe, D. Queloz, J. Rodriguez, D. Segransan, I. Skillen, B. Smalley, K. G. Stassun, S. Udry, R. G. West, P. J. Wheatley

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)3392-3401
Number of pages10
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
Early online date17 Apr 2014
Publication statusPublished - 1 Jun 2014


  • Techniques: photometric
  • Techniques: radial velocities
  • Stars: individual: WASP-13
  • Stars: individual: WASP-32
  • Planetary systems
  • Spin-orbit Misalignment
  • Transiting exoplanets
  • Hot-Jupiter
  • Host stars
  • Rotation periods
  • Polar orbit
  • Time-series
  • Spaced data
  • Systems
  • Planet


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