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SUMMARY:Secular instability: organization of planetary systems and the ori
 gin of hot Jupiters - Wu\, Y (Toronto)
DTSTART:20090820T092000Z
DTEND:20090820T094000Z
UID:TALK19473@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:In a planetary system where planets are well spaced and intera
 ct only through their secular (i.e.\, non-resonant) perturbations\, there 
 exists a nonlinear instability that leads to chaotic behaviour. Some plane
 ts (the most unstable ones) may gradually obtain very large values of ecce
 ntricities and/or inclinations. We elucidate the condition under which thi
 s occurs. \n\nWhen a most unstable planet is removed from the system\, eit
 her through close encounter with another planet\, or through close encount
 er with the star (where tidal effects might kick in)\, the remaining plane
 tary system becomes increasingly more stable. This\, as opposed to planet-
 planet scattering\, may explain the stable architecture of the observed sy
 stems. \n\nIn the case of the most unstable planet moving in toward close 
 encounter with the star\, its pericentre dipping may be tidally stalled ar
 ound a few stellar radii. When these orbits are tidally circularized\, we 
 obtain hot jupiters (or hot neptunes). This scenario for hot jupiter forma
 tion explains a variety of observed phenomena\, including correlations bet
 ween planet mass and semi-major axis\, coplanarity of planet orbit and ste
 llar spin\, as well as the paucity of second planets around hot jupiters.
LOCATION:Seminar Room 1 Newton Institute
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