BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Formation of heavy-element rich giant planets - Genda\, H (Tokyo I
 nstitute of Technology)
DTSTART:20090818T134000Z
DTEND:20090818T140000Z
UID:TALK19512@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:More than twenty extrasolar planets are known to transit their
  star. >From planetary radius observed by the transit method and planetary
  mass observed by the radial velocity method\, one can determine the densi
 ties of the extrasolar planets. The density of the planet informs us about
  the planetary interior. According to calculation of the interior structur
 e of gas giant planet by Guillot et al. (2006)\, the core mass and core ma
 ss ratio in the planets increases with the metallicity of their star ([Fe/
 H]). This dependency seems to be reasonable\, because the star with higher
  [Fe/H] had the protoplanetary disk with enough solid materials to form mo
 re heavy element-rich planet. However\, the simple formation theory of gas
  giant planets cannot fully explain this dependency. We have performed the
  smoothed particle hydrodynamic (SPH) simulations of collisions between tw
 o gas giant planets. Changes in masses of the ice/rock core and the H/He e
 nvelope due to the collisions are investigated. The main aim of this study
  is to constrain the origin and probability of a class of extrasolar hot J
 upiters that have much larger cores and/or higher core/envelope mass ratio
 s than those predicted by theories of accretion of gas giant planets. A ty
 pical example is HD 149026b. Theoretical models of the interior of HD 1490
 26b (Sato et al. 2005\; Fortney et al. 2006\; Ikoma et al. 2006) predict t
 hat the planet contains a huge core of 50-80 Earth masses relative to the 
 total mass of 110 Earth masses. Our SPH simulations demonstrate that such 
 a gas giant is produced by a collision with an impact velocity of typicall
 y more than 2.5 times escape velocity and an impact angle of typically les
 s than 10 degrees\, which results in an enormous loss of the envelope gas 
 and complete accretion of both cores.
LOCATION:Seminar Room 1 Newton Institute
END:VEVENT
END:VCALENDAR