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Title: On the viability of the magnetorotational instability in circumplanetary disks

Abstract

We examine whether the magnetorotational instability (MRI) can serve as a mechanism of angular momentum transport in circumplanetary disks. For the MRI to operate the ionization degree must be sufficiently high and the magnetic pressure must be sufficiently lower than the gas pressure. We calculate the spatial distribution of the ionization degree and search for the MRI-active region where the two criteria are met. We find that there can be thin active layers at the disk surface depending on the model parameters, however, we find hardly any region which can sustain well-developed MRI turbulence; when the magnetic field is enhanced by MRI turbulence at the disk surface layer, a magnetically dominated atmosphere encroaches on a lower altitude and a region of well-developed MRI turbulence becomes smaller. We conclude that if there are no angular momentum transfer mechanisms other than MRI in gravitationally stable circumplanetary disks, gas is likely to pile up until disks become gravitationally unstable, and massive disks may survive for a long time.

Authors:
; ;  [1];  [2]
  1. Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602 (Japan)
  2. Institute of Low Temperature Science, Hokkaido University, Sapporo 066-0819 (Japan)
Publication Date:
OSTI Identifier:
22357110
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 785; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ALTITUDE; ANGULAR MOMENTUM; ANGULAR MOMENTUM TRANSFER; ATMOSPHERES; DUSTS; INSTABILITY; LAYERS; MAGNETIC FIELDS; NMR IMAGING; PLANETS; PROTOPLANETS; SATELLITES; SPATIAL DISTRIBUTION; SURFACES; TURBULENCE; VIABILITY

Citation Formats

Fujii, Yuri I., Okuzumi, Satoshi, Inutsuka, Shu-ichiro, and Tanigawa, Takayuki, E-mail: yuri.f@nagoya-u.jp. On the viability of the magnetorotational instability in circumplanetary disks. United States: N. p., 2014. Web. doi:10.1088/0004-637X/785/2/101.
Fujii, Yuri I., Okuzumi, Satoshi, Inutsuka, Shu-ichiro, & Tanigawa, Takayuki, E-mail: yuri.f@nagoya-u.jp. On the viability of the magnetorotational instability in circumplanetary disks. United States. doi:10.1088/0004-637X/785/2/101.
Fujii, Yuri I., Okuzumi, Satoshi, Inutsuka, Shu-ichiro, and Tanigawa, Takayuki, E-mail: yuri.f@nagoya-u.jp. 2014. "On the viability of the magnetorotational instability in circumplanetary disks". United States. doi:10.1088/0004-637X/785/2/101.
@article{osti_22357110,
title = {On the viability of the magnetorotational instability in circumplanetary disks},
author = {Fujii, Yuri I. and Okuzumi, Satoshi and Inutsuka, Shu-ichiro and Tanigawa, Takayuki, E-mail: yuri.f@nagoya-u.jp},
abstractNote = {We examine whether the magnetorotational instability (MRI) can serve as a mechanism of angular momentum transport in circumplanetary disks. For the MRI to operate the ionization degree must be sufficiently high and the magnetic pressure must be sufficiently lower than the gas pressure. We calculate the spatial distribution of the ionization degree and search for the MRI-active region where the two criteria are met. We find that there can be thin active layers at the disk surface depending on the model parameters, however, we find hardly any region which can sustain well-developed MRI turbulence; when the magnetic field is enhanced by MRI turbulence at the disk surface layer, a magnetically dominated atmosphere encroaches on a lower altitude and a region of well-developed MRI turbulence becomes smaller. We conclude that if there are no angular momentum transfer mechanisms other than MRI in gravitationally stable circumplanetary disks, gas is likely to pile up until disks become gravitationally unstable, and massive disks may survive for a long time.},
doi = {10.1088/0004-637X/785/2/101},
journal = {Astrophysical Journal},
number = 2,
volume = 785,
place = {United States},
year = 2014,
month = 4
}
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