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ASTRONOMY

 
 

ExtraSolar Planets: New Clues for Planet Formation

William Cochran (Texas)

Approximately 100 planetary-mass companions to solar type stars have been discovered using high precision radial velocity techniques. Recent discoveries include planets with minimum masses below that of Saturn, many systems with indications of multiple planets, and a jovian-mass companion to one of the nearest stars to the sun, epsilon Eridani. This talk will review the present status of extrasolar planetary systems. The distribution of masses and orbital properties offers interesting clues to the origin and evolution of these systems. The apparent tendency of extrasolar planets to be found preferentially around stars of high heavy element abundance will be examined. The very severe selection effects in the radial velocity discoveries will be discussed. The past years has also seen the emergence of a new technique for study of extra-solar planets in the form of high precision photometry of planetary transits across the disk of the parent star. We will summarize many of the recent results in transits in the HD209458 system and in the globular cluster 47 Tuc. The near-term future offers many exciting prospects for new types of planet discoveries. We will briefly discuss these prospects, and the added information that they will offer on the origin and evolution of extrasolar planetary systems.