TY - JOUR
T1 - WIND-DRIVEN ACCRETION in TRANSITIONAL PROTOSTELLAR DISKS
AU - Wang, Lile
AU - Goodman, Jeremy J.
N1 - Funding Information:
This work was supported by NASA Origins of Solar Systems grant NNX10AH37G.
Publisher Copyright:
© 2017. The American Astronomical Society. All rights reserved.
PY - 2017/1/20
Y1 - 2017/1/20
N2 - Transitional protostellar disks have inner cavities that are heavily depleted in dust and gas, yet most of them show signs of ongoing accretion, often at rates comparable to full disks. We show that recent constraints on the gas surface density in a few well-studied disk cavities suggest that the accretion speed is at least transsonic. We propose that this is the natural result of accretion driven by magnetized winds. Typical physical conditions of the gas inside these cavities are estimated for plausible X-ray and FUV radiation fields. The gas near the midplane is molecular and predominantly neutral, with a dimensionless ambipolar parameter in the right general range for wind solutions of the type developed by Königl, Wardle, and others. That is to say, the density of ions and electrons is sufficient for moderately good coupling to the magnetic field, but it is not so good that the magnetic flux needs to be dragged inward by the accreting neutrals.
AB - Transitional protostellar disks have inner cavities that are heavily depleted in dust and gas, yet most of them show signs of ongoing accretion, often at rates comparable to full disks. We show that recent constraints on the gas surface density in a few well-studied disk cavities suggest that the accretion speed is at least transsonic. We propose that this is the natural result of accretion driven by magnetized winds. Typical physical conditions of the gas inside these cavities are estimated for plausible X-ray and FUV radiation fields. The gas near the midplane is molecular and predominantly neutral, with a dimensionless ambipolar parameter in the right general range for wind solutions of the type developed by Königl, Wardle, and others. That is to say, the density of ions and electrons is sufficient for moderately good coupling to the magnetic field, but it is not so good that the magnetic flux needs to be dragged inward by the accreting neutrals.
KW - accretion, accretion disks
KW - astrochemistry
KW - circumstellar matter
KW - planetary systems
KW - planets and satellites: formation
KW - protoplanetary disks
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U2 - 10.3847/1538-4357/835/1/59
DO - 10.3847/1538-4357/835/1/59
M3 - Article
AN - SCOPUS:85011266694
SN - 0004-637X
VL - 835
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 59
ER -