The planet search program at the ESO Coudé Echelle spectrometer^*

II. The α Centauri system: Limits for planetary companions

¹ Universität Wien, Institut für Astronomie, Türkenschanzstr. 17, 1180 Wien, Austria
² European Southern Observatory, Casilla 19001, Vitacura, Santiago 19, Chile
³ Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany
⁴ Universität Heidelberg, Institut für Theoretische Astrophysik, Tiergartenstr. 15, 69121 Heidelberg, Germany
⁵ McDonald Observatory, The University of Texas at Austin, Austin, TX 78712-1083, USA

Corresponding author: M. Endl, endl@astro.univie.ac.at

Received: 11 April 2001
Accepted: 19 May 2001

Abstract

In this article we present the results of the planet search program carried out at the ESO Coudé Echelle Spectrometer (CES) for components A and B of the α 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 [CITE]) we can now set strong constraints on the existence of Jupiter-mass-type planets in the α Centauri system.