1 Introduction

Following the discovery in 1995 of the planet orbiting 51Peg (Mayor & Queloz 1995), we have witnessed a complete revolution in the field of extra-solar planets. More than 70 other exoplanets were unveiled since then, all by means of high-precision radial-velocity techniques. These discoveries comprise 7 multi-planetary systems.

Two of the most prolific and precise planet search programmes are carried out by the Geneva group in both hemispheres, using the CORALIE spectrograph at the 1.2-m Euler Swiss telescope (e.g. Udry et al. 2000), at La Silla observatory (ESO, Chile) and, in collaboration with French colleagues, the ELODIE spectrograph (Baranne et al. 1996) at the 1.93-m telescope of the Haute-Provence observatory (France). In total, these two instruments have discovered (or in a few cases co-discovered) 32 planets, i.e. about half of the known systems.

Apart from a "few'' exceptions, most of the extra-solar planets found to date have relatively short period orbits (shorter than 1year). There are basically two reasons for this "bias''. First, radial-velocity techniques are more sensitive to close companions; a long period companion must have, with respect to a shorter period one, a higher mass to produce a radial-velocity variation with the same amplitude. Second, to detect a long period planet one needs to follow a star during several seasons with the necessary long term precision. However, the ever increasing accuracy and continuity of some of the current radial-velocity surveys are now permitting to unveil more and more long period companions. In this paper we present two such candidates, recently discovered in the context of the CORALIE programme, namely the companions around HD28185 and HD213240.