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SUMMARY:Giant planet formation in radially structured discs - Gavin Colema
 n (University of Bern) 
DTSTART:20171113T140000Z
DTEND:20171113T150000Z
UID:TALK82191@talks.cam.ac.uk
CONTACT:Dr. Yufeng Lin
DESCRIPTION:Observations have demonstrated the existence of a significant 
 population of compact systems comprised of super-Earths and Neptune-mass p
 lanets\, and a population of gas giants that appear to occur primarily in 
 either short-period (%<%10 days) or longer period (>100 days) orbits. The 
 broad diversity of system architectures raises the question of whether or 
 not the same formation processes operating in standard disc models can exp
 lain these planets\, or if different scenarios are required instead to exp
 lain the widely differing architectures. To explore this issue\, we presen
 t recent results from a comprehensive suite of N-body simulations of plane
 tary system formation that include the following physical processes: N-bod
 y interactions between planetary embryos and planetesimals\; type I and II
  migration\; gas accretion onto planetary cores\; self-consistent viscous 
 disc evolution and disc removal through photo-evaporation. Results indicat
 e that the formation and survival of compact systems of super-Earths and N
 eptune-mass planets occur commonly in disc models where a simple prescript
 ion for the disc viscosity is assumed\, but such models never lead to the 
 formation and survival of gas giant planets due to migration into the star
 . Inspired in part by the ALMA observations of HL Tau\, and by MHD simulat
 ions that display the formation of long-lived zonal flows\, we have explor
 ed the consequences of assuming that the disc viscosity varies in both tim
 e and space. We find that the radial structuring of the disc leads to cond
 itions in which systems of giant planets are able to form and survive. Fur
 thermore\, these giants generally occupy those regions of the mass-period 
 diagram that are densely populated by the observed gas giants\, suggesting
  that the planet traps generated by radial structuring of protoplanetary d
 iscs may be a necessary ingredient for forming giant planets.
LOCATION:MR14\,  Centre for Mathematical Sciences\, Wilberforce Road\, Cam
 bridge
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