2011/11/21 by Simon Albrecht, Joshua N. Winn, R. Paul Butler +6 · 3 citations
Physics and Astronomy · #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Differential rotation #Geometry #Jupiter (rocket family) #Physics #Planet #Radial velocity #Rotation (mathematics) #Rotation period #Spectral line #Spectrograph #Stars #Stellar rotation #Stellar, planetary, and galactic studies #astro-ph.EP #astro-ph.SR
paper · pdf · doi:10.1088/0004-637x/744/2/189
ApJ accepted, 9 pages, 9 figures
arxiv created 2011/11/21 · openalex publication_date 2011/12/22 · arxiv updated 2015/06/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We measure a tilt of 86° ± 6° between the sky projections of the rotation axis of the WASP-7 star and the orbital axis of its close-in giant planet. This measurement is based on observations of the Rossiter–McLaughlin (RM) effect with the Planet Finder Spectrograph on the Magellan II telescope. The result conforms with the previously noted pattern among hot-Jupiter hosts, namely, that the hosts lacking thick convective envelopes have high obliquities. Because the planet's trajectory crosses a wide range of stellar latitudes, observations of the RM effect can in principle reveal the stellar differential rotation profile; however, with the present data the signal of differential rotation could not be detected. The host star is found to exhibit radial-velocity noise ("stellar jitter") with an amplitude of ≈30 m s −1 over a timescale of days.