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| Highlights from the Southern Sky: Searches for exoplanets at ESO (European Southern Observatory)
Contact: Michel Mayor (Geneva Observatory)
In the last twelve months some 14 exoplanets (*) have been detected and characterized by our team. Only after one year of operation at the ESO-La Silla Observatory, the new HARPS spectrometer has confirmed its unique sensitivity to measure changes of stellar velocities as tiny as one meter per second. This extremely high sensitivity opens the possibility to detect very light planets with masses comparable to Neptune or even lighter, such as the 14 Earth mass planet orbiting Mu Ara. (*) of which 8 new ones are to be announced in Aspen by Lovis et al, Moutou et al., and Eggenberger et al. Stars could be smaller than planets The OGLE survey has revealed about 150 stars candidates for planetary transits. With the 8.2 meter VLT Telescope at Paranal Observatory, we have already derived precise velocities for 60 of these candidates. Four of them have been shown to have orbiting exoplanets for which masses and radii have been obtained. These four planets (in addition to three others from previous studies) permit the determination of an observed relation between the radii and masses of exoplanets. The recent measurements of the radius of OGLE-Tr-122 by Pont et al. (in press), a star at the extreme bottom of the stellar main sequence, reveal a diameter smaller than the exoplanet diameters. Precise velocity measurements will be mandatory to confirm any planetary
candidates from future transit search programs (such as the space
missions COROT and Kepler).
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