The HR 8799 Planetary System
Christian Marois
Herzberg Institute of Astrophysics

Almost 15 years ago the first unambiguous direct detection of a substellar object around a star (Gl229B) was made. Several teams have since then pursued ambitious adaptive optics surveys on large telescopes, but only several brown dwarfs and a few possible candidate planets have been detected so far at generally wide >100 AU separations - it is unlikely that these have formed in a disk like the planets of our solar system and are probably the result of the binary star formation process. The essentially null result of these surveys, in contrast with the very successful radial velocity searches <5 AU, is suggesting that massive Jupiter-like planets are rare >20 AU around stars. The year 2008 marks then end of this long drought with the direct detection of planets around A-type stars. One of these discoveries, the HR8799 planetary system made at the Gemini North and Keck telescopes, is the first multi-planet system portrait and also the first direct detection of thermal emission of confirmed planets in orbit around a star. This system also shows convincing evidences that the three planets formed in a disk. The HR8799 system discovery marks an important step forward in the direct characterization of Jovians to Earth-like planets with future instrumentations and large ELTs.

Date:	Jeudi, 14 janvier 2010
Time:	11:30
Where:	Université de Montréal
	Pavillon Roger-Gaudry, Local D-460
Contact:	René Doyon