Volume 569, September 2014
|Number of page(s)||11|
|Section||Planets and planetary systems|
|Published online||24 September 2014|
Detecting the spin-orbit misalignment of the super-Earth 55 Cancri e⋆
1 Institut d’astrophysique de Paris,
UMR 7095 CNRS, Université Pierre & Marie Curie, 98bis boulevard Arago, 75014
2 Observatoire de Haute-Provence, CNRS/OAMP, 04870 Saint-Michel-l’Observatoire, France
Accepted: 25 June 2014
We present time-resolved spectroscopy of transits of the super-Earth 55 Cnc e using HARPS-N observations. We devised an empirical correction for the “color effect” on the radial velocity residuals from the Keplerian fit, which significantly improves their dispersion with respect to the HARPS-N pipeline standard data reduction. Using our correction, we were able to detect the smallest Rossiter-McLaughlin anomaly amplitude of an exoplanet so far (~60 cm/s). The super-Earth 55 Cnc e is also the smallest exoplanet with a Rossiter-McLaughlin anomaly detection. We measured the sky-projected obliquity λ = 72.4-11.5+12.7°, indicating that the planet orbit is prograde, highly misaligned and nearly polar compared to the stellar equator. The entire 55 Cancri system may have been highly tilted by the presence of a stellar companion.
Key words: Planets and satellites: dynamical evolution and stability / techniques: radial velocities / stars: individual: 55 Cancri
Table 4 is available in electronic form at http://www.aanda.org
© ESO, 2014
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