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SUMMARY:Dynamics and planet formation at wide separations: HR8799 - Murray
 -Clay\, R (Harvard Smithsonian Center)
DTSTART:20091111T145000Z
DTEND:20091111T151000Z
UID:TALK21419@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:The three gas giants directly-imaged orbiting HR 8799 comprise
  the first multi-planet system detected at wide separations around a main 
 sequence star. Core accretion scenarios\, already strained at the outer li
 mits of our solar system\, have difficulty explaining planet formation at 
 the larger distances of the HR 8799 planets\, even around a central A star
 . Though most plausible for massive planets at large separations\, formati
 on by gravitational instability requires that the system's protoplanetary 
 disk passed through a fine-tuned region of parameter space at its transiti
 on from the Class I to the Class II phase. Orbital stability requirements 
 imply that the HR 8799 planets occupy at least one and possibly two mean m
 otion resonances\, suggesting that they migrated toward one another and ma
 y have migrated substantially from their formation locations. I will discu
 ss how the HR 8799 system constrains the formation and migration of distan
 t planets.
LOCATION:Satellite
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