Poster
X. Dumusque, F. Pepe, C. Lovis, D. Ségransan, W. Benz, F. Bouchy, M. Mayor, D. Queloz, N. C. Santos, S. Udry
Abstract
Since a long time, Alpha Cen B (HD128621) has been qualified as the best target to search for an habitable Earth-like planet. The brightness of the star (V = 1.3) allowing to reach a very high signal-to-noise ratio, its low activity, its spectral type (K1V) and the proximity of it have made of Alpha Cen B the holy grail of exoplanet astronomers.
However, recent HARPS measurements of Alpha Cen B have show that the star is not as quiet as expected. Since 4 years, the activity level of the star has raise, increasing strongly the stellar jitter due to the presence of magnetic spots on the stellar surface.
Due to a high frequency sampling (2 to 3 measurements per night every night) and the very high-precision of the HARPS spectrograph (below 80 cm/s), it is possible to see the magnetic cycle and the day-by-day variation of the spot induced noise. The high quality of these data allows us to correct radial velocities (RVs) from these noises.
Extreme Solar Systems II
Moran, Wyoming, U.S.A.
2011 September
