The planet search program at the ESO Coude Echelle spectrometer -: II.: The α Centauri system:: Limits for planetary companions

In this article we present the results of the planet search program carried out at the ESO Coude Echelle Spectrometer (CES) for components A and B of the alpha Centauri system. Since November 1992 we have obtained high precision differential radial velocities (RVs) for both stars. We demonstrate that, after subtraction of the binary orbital motion, no additional residual RV signal is present within our detection limits, which could have been attributed to giant planets orbiting either of the two stars. We performed numerical simulations to determine the detection threshold of the CES survey for planets around both stars. In combination with known dynamical limitations for stable planetary orbits (Wiegert & Holman 1997) we can now set strong constraints on the existence of Jupiter-mass-type planets in the alpha Centauri system.