Solar-like oscillations in the K1 dwarf star (alpha) Cen B

The K1 dwarf (alpha) Cen B was observed with the CORALIE spectrograph on the 1.2-m Swiss telescope at La Silla in April 2003. Thirteen nights of observations have made it possible to collect 3626 radial velocity measurements with a standard deviation of 1.4 m s^-1 exhibiting a mean noise level in the amplitude spectrum of only 3.75 cm s^-1. Twelve oscillation modes have been identified in the power spectrum between 3 and 4.6 mHz with amplitudes in the range 8.7 to 13.7 cm s^-1 and showing a regularity with a large separation of 161.1 (mu) Hz. A preliminary discussion on the physical parameters of the (alpha) Cen binary system is presented.