Top: calcium activity index log () time series of α Cen B in 2010. The observations span two consecutive rotational phases, where P_rot = 35.8 days. Middle: RV time series over the same time interval. We show a quadratic trend fitted to the data (red) that corresponds to the binary contribution of α Cen A and a possible activity cycle (Dumusque 2012). Bottom: RV residuals after removing the quadratic trend, which present an RV rms of 2.1 m s⁻¹. These RV residuals are strongly correlated to the calcium activity index and therefore are significantly affected by stellar activity.