Protostars and Planets VI, Heidelberg, July 15-20, 2013

Poster 2S050

Magnetized Accretion and Dead Zones in Protoplanetary disks

Dzyurkevich, Natalia (Laboratoire de radioastronomie, UMR 8112 du CNRS, Ecole Normale Superieure et Observatoire de Paris, 24 rue de Lhomond, 75231, Paris Cedex 05, France)
Turner, Neal J. (Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, USA)
Henning, Thomas (Max Planck Institute for Astronomy, Koenigstuhl 17, 69117 Heidelberg, Germany)
Kley, Wilhelm (University of Tuebingen, Auf der Morgenstelle 10, Tuebingen, 72076 Germany)

The edges of magnetically-dead zones in protostellar disks have been proposed as locations where density bumps may arise, trapping planetesimals and helping form planets. Magneto-rotational turbulence in magnetically-active zones provides both accretion of gas on the star and transport of mass to the dead zone. We investigate the location of the magnetically-active regions in a protostellar disk around a solar-type star, varying the parameters like dust-to-gas ratio. The dead zone is in most cases defined by the ambipolar diffusion. In our maps, the dead zone takes a variety of shapes, including a fish-tail pointing away from the star and islands located on and off the midplane. The corresponding accretion rates vary with radius, indicating locations where the surface density will increase over time, and others where it will decrease. We show that density bumps do not readily grow near the dead zone\'s outer edge, independently of the disk parameters and the dust properties. Instead, the accretion rate peaks at the radius where the gas-phase metals freeze out. This could lead to clearing a valley in the surface density, and to a trap for pebbles located just outside the metal freeze-out line. Here, we provide the fitting formula for the metal line and consider the cojoint impact of metal ans snow lines on the shape of the dead zone.

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