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SUMMARY:On the migration of giant mass planets in 3D disks accreting from 
 surface layers
DTSTART;VALUE=DATE-TIME:20200513T115500Z
DTEND;VALUE=DATE-TIME:20200513T121500Z
DTSTAMP;VALUE=DATE-TIME:20240704T115619Z
UID:indico-contribution-44@meetings.aip.de
DESCRIPTION:Speakers: Elena Lega ()\nThe classic view of a viscous disk\, 
 where viscosity is generated by strong turbulence driven by the magneto ro
 tational instability\, is challenged by modern magneto-hydrodynamic simula
 tions. Disks are probably much less viscous than previously thought. Never
 theless\, disks cannot be in-viscid\, a minimum viscosity is set for examp
 le by the so-called vertical shear instability (VSI). In addition\, disk w
 inds remove angular momentum from thin surface layers of the proto-planeta
 ry disk\, promoting  fast radial transport of gas towards the central star
  in these layers. This radial transport accounts for the observed stars' a
 ccretion rate.\nIn a classical viscous disk with radial transport correspo
 nding to  observed stellar accretion rate\, giant planets migrate towards 
 the star and easily become hot Jupiters with short orbital period.  Howeve
 r\, the majority of observed giant planets have distances of 1-3AU from th
 eir parent star.\nThis contradiction has been investigated looking at a va
 riety of migrations mechanisms\, but no general mechanism to reduce planet
  migration has been found.\nThe new paradigm of disks  with small bulk vis
 cosity and fast radial advection in surface offers a different perspective
  of the problem.\nConsequently\, we perform 3D numerical simulations using
  the FARGOCA code. We simulate the effect of disk wind by imposing a loss 
 of angular momentum generating a desired mass flux  in a thin surface laye
 r.\nWe show that  planets migration is only marginally affected by the fas
 t gas in the thin layers and that the migration speed is mainly regulated 
 by the bulk viscosity of the disk. However\, the migration rate measured w
 ith a bulk viscosity of alpha=1.e-4 (typically of the order of that genera
 ted by the VSI in the outer disk)  is still too fast to understand  the ob
 served radial distribution of extra-solar planets.  Decreasing further the
  viscosity seems necessary for the understanding of the  observations.\n\n
 https://meetings.aip.de/event/1/contributions/44/
LOCATION:Leibniz Institute for Astrophysics Potsdam (AIP) Lecture Hall
URL:https://meetings.aip.de/event/1/contributions/44/
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