Magnetorotational Instability in Protoplanetary Disks. II. Ionization State and Unstable Regions

Citations Over TimeTop 10% of 2000 papers

Abstract

We investigate where in protoplanetary disks magnetorotational instability operates, which can cause angular momentum transport in the disks. We investigate the spatial distribution of various charged particles and the unstable regions for a variety of models for protoplanetary disks taking into account the recombination of ions and electrons at grain surfaces, which is an important process in most parts of the disks. We find that for all the models there is an inner region which is magnetorotationally stable due to ohmic dissipation. This must make the accretion onto the central star non-steady. For the model of the minimum-mass solar nebula, the critical radius, inside of which the disk is stable, is about 20 AU, and the mass accretion rate just outside the critical radius is 10^{-7} - 10^{-6} M_{\odot} yr^{-1}. The stable region is smaller in a disk of lower column density. Dust grains in protoplanetary disks may grow by mutual sticking and may sediment toward the midplane of the disks. We find that the stable region shrinks as the grain size increases or the sedimentation proceeds. Therefore in the late evolutionary stages, protoplanetary disks can be magnetorotationally unstable even in the inner regions.

Related Papers

• → The interplay between X-ray photoevaporation and planet formation(2013)99 cited
• → EXTERNAL PHOTOEVAPORATION OF THE SOLAR NEBULA. II. EFFECTS ON DISK STRUCTURE AND EVOLUTION WITH NON-UNIFORM TURBULENT VISCOSITY DUE TO THE MAGNETOROTATIONAL INSTABILITY(2015)20 cited
• → Origin of nonlinearity and plausible turbulence by hydromagnetic transient growth in accretion disks: Faster growth rate than magnetorotational instability(2015)11 cited
• → The interplay between X-ray photoevaporation and planet formation(2013)