WIND-DRIVEN ACCRETION IN PROTOPLANETARY DISKS. I. SUPPRESSION OF THE MAGNETOROTATIONAL INSTABILITY AND LAUNCHING OF THE MAGNETOCENTRIFUGAL WIND

Xuening, Bai

doi:10.1088/0004-637X/769/1/76

Title: WIND-DRIVEN ACCRETION IN PROTOPLANETARY DISKS. I. SUPPRESSION OF THE MAGNETOROTATIONAL INSTABILITY AND LAUNCHING OF THE MAGNETOCENTRIFUGAL WIND

Full Record
Other Related Research

Abstract

We perform local, vertically stratified shearing-box MHD simulations of protoplanetary disks (PPDs) at a fiducial radius of 1 AU that take into account the effects of both Ohmic resistivity and ambipolar diffusion (AD). The magnetic diffusion coefficients are evaluated self-consistently from a look-up table based on equilibrium chemistry. We first show that the inclusion of AD dramatically changes the conventional picture of layered accretion. Without net vertical magnetic field, the system evolves into a toroidal field dominated configuration with extremely weak turbulence in the far-UV ionization layer that is far too inefficient to drive rapid accretion. In the presence of a weak net vertical field (plasma {beta} {approx} 10{sup 5} at midplane), we find that the magnetorotational instability (MRI) is completely suppressed, resulting in a fully laminar flow throughout the vertical extent of the disk. A strong magnetocentrifugal wind is launched that efficiently carries away disk angular momentum and easily accounts for the observed accretion rate in PPDs. Moreover, under a physical disk wind geometry, all the accretion flow proceeds through a strong current layer with a thickness of {approx}0.3H that is offset from disk midplane with radial velocity of up to 0.4 times the sound speed. Both Ohmic resistivitymore »« less

Authors:: Xuening, Bai

Publication Date:: Mon May 20 00:00:00 EDT 2013

OSTI Identifier:: 22126611

Resource Type:: Journal Article

Journal Name:: Astrophysical Journal

Additional Journal Information:: Journal Volume: 769; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X

Country of Publication:: United States

Language:: English

Subject:: 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; AMBIPOLAR DIFFUSION; ANGULAR MOMENTUM; EQUILIBRIUM; INSTABILITY; LAMINAR FLOW; LAYERS; MAGNETIC FIELDS; MAGNETIC FLUX; MAGNETOHYDRODYNAMICS; PENETRATION DEPTH; PROTOPLANETS; RADIAL VELOCITY; SIMULATION; STELLAR WINDS; THICKNESS; TURBULENCE

Citation Formats


                    Xuening, Bai, and Stone, James M., E-mail: xbai@cfa.harvard.edu. WIND-DRIVEN ACCRETION IN PROTOPLANETARY DISKS. I. SUPPRESSION OF THE MAGNETOROTATIONAL INSTABILITY AND LAUNCHING OF THE MAGNETOCENTRIFUGAL WIND.  United States: N. p., 2013. 
        Web.  doi:10.1088/0004-637X/769/1/76.

Copy to clipboard


                    Xuening, Bai, & Stone, James M., E-mail: xbai@cfa.harvard.edu. WIND-DRIVEN ACCRETION IN PROTOPLANETARY DISKS. I. SUPPRESSION OF THE MAGNETOROTATIONAL INSTABILITY AND LAUNCHING OF THE MAGNETOCENTRIFUGAL WIND.  United States.  https://doi.org/10.1088/0004-637X/769/1/76

Copy to clipboard


                    Xuening, Bai, and Stone, James M., E-mail: xbai@cfa.harvard.edu. 2013.  
        "WIND-DRIVEN ACCRETION IN PROTOPLANETARY DISKS. I. SUPPRESSION OF THE MAGNETOROTATIONAL INSTABILITY AND LAUNCHING OF THE MAGNETOCENTRIFUGAL WIND".  United States.  https://doi.org/10.1088/0004-637X/769/1/76.

Copy to clipboard


                    
@article{osti_22126611,

  title        = {WIND-DRIVEN ACCRETION IN PROTOPLANETARY DISKS. I. SUPPRESSION OF THE MAGNETOROTATIONAL INSTABILITY AND LAUNCHING OF THE MAGNETOCENTRIFUGAL WIND},

  author       = {Xuening, Bai and Stone, James M., E-mail: xbai@cfa.harvard.edu},

  abstractNote = {We perform local, vertically stratified shearing-box MHD simulations of protoplanetary disks (PPDs) at a fiducial radius of 1 AU that take into account the effects of both Ohmic resistivity and ambipolar diffusion (AD). The magnetic diffusion coefficients are evaluated self-consistently from a look-up table based on equilibrium chemistry. We first show that the inclusion of AD dramatically changes the conventional picture of layered accretion. Without net vertical magnetic field, the system evolves into a toroidal field dominated configuration with extremely weak turbulence in the far-UV ionization layer that is far too inefficient to drive rapid accretion. In the presence of a weak net vertical field (plasma {beta} {approx} 10{sup 5} at midplane), we find that the magnetorotational instability (MRI) is completely suppressed, resulting in a fully laminar flow throughout the vertical extent of the disk. A strong magnetocentrifugal wind is launched that efficiently carries away disk angular momentum and easily accounts for the observed accretion rate in PPDs. Moreover, under a physical disk wind geometry, all the accretion flow proceeds through a strong current layer with a thickness of {approx}0.3H that is offset from disk midplane with radial velocity of up to 0.4 times the sound speed. Both Ohmic resistivity and AD are essential for the suppression of the MRI and wind launching. The efficiency of wind transport increases with increasing net vertical magnetic flux and the penetration depth of the FUV ionization. Our laminar wind solution has important implications on planet formation and global evolution of PPDs.},

  doi          = {10.1088/0004-637X/769/1/76},

  url          = {https://www.osti.gov/biblio/22126611},
  journal      = {Astrophysical Journal},

  issn         = {0004-637X},

  number       = 1,

  volume       = 769,

  place        = {United States},

  year         = {Mon May 20 00:00:00 EDT 2013},

  month        = {Mon May 20 00:00:00 EDT 2013}

}

Copy to clipboard

Journal Article:

https://doi.org/10.1088/0004-637X/769/1/76

Other availability

Find in Google Scholar

Search WorldCat to find libraries that may hold this journal

Save / Share:

Export Metadata

Save to My Library

Similar records in OSTI.GOV collections:

WIND-DRIVEN ACCRETION IN PROTOPLANETARY DISKS. II. RADIAL DEPENDENCE AND GLOBAL PICTURE

Journal Article

Non-ideal magnetohydrodynamical effects play a crucial role in determining the mechanism and efficiency of angular momentum transport as well as the level of turbulence in protoplanetary disks (PPDs), which are the key to understanding PPD evolution and planet formation. It was shown in our previous work that at 1 AU, the magnetorotational instability (MRI) is completely suppressed when both ohmic resistivity and ambipolar diffusion (AD) are taken into account, resulting in a laminar flow with accretion driven by magnetocentrifugal wind. In this work, we study the radial dependence of the laminar wind solution using local shearing-box simulations. The scaling relationmore »« less
https://doi.org/10.1088/0004-637X/772/2/96
HALL EFFECT CONTROLLED GAS DYNAMICS IN PROTOPLANETARY DISKS. II. FULL 3D SIMULATIONS TOWARD THE OUTER DISK

Journal Article Bai, Xue-Ning - Astrophysical Journal

We perform three-dimensional stratified shearing-box magnetohydrodynamic (MHD) simulations on the gas dynamics of protoplanetary disks with a net vertical magnetic flux of B {sub z0}. All three nonideal MHD effects, Ohmic resistivity, the Hall effect, and ambipolar diffusion, are included in a self-consistent manner based on equilibrium chemistry. We focus on regions toward outer disk radii, from 5 to 60 AU, where Ohmic resistivity tends to become negligible, ambipolar diffusion dominates over an extended region across the disk height, and the Hall effect largely controls the dynamics near the disk midplane. We find that at around R = 5 AU the systemmore »« less
https://doi.org/10.1088/0004-637X/798/2/84
LOCAL STUDY OF ACCRETION DISKS WITH A STRONG VERTICAL MAGNETIC FIELD: MAGNETOROTATIONAL INSTABILITY AND DISK OUTFLOW

Journal Article Bai, Xue-Ning - Astrophysical Journal

We perform three-dimensional, vertically-stratified, local shearing-box ideal MHD simulations of the magnetorotational instability (MRI) that include a net vertical magnetic flux, which is characterized by midplane plasma {beta}{sub 0} (ratio of gas to magnetic pressure). We have considered {beta}{sub 0} = 10{sup 2}, 10{sup 3}, and 10{sup 4}, and in the first two cases the most unstable linear MRI modes are well resolved in the simulations. We find that the behavior of the MRI turbulence strongly depends on {beta}{sub 0}: the radial transport of angular momentum increases with net vertical flux, achieving {alpha} {approx} 0.08 for {beta} = 10{sup 4}more »« less
https://doi.org/10.1088/0004-637X/767/1/30
THE ROLE OF TINY GRAINS ON THE ACCRETION PROCESS IN PROTOPLANETARY DISKS

Journal Article

Tiny grains such as polycyclic aromatic hydrocarbons (PAHs) have been thought to dramatically reduce the coupling between the gas and magnetic fields in weakly ionized gas such as in protoplanetary disks (PPDs) because they provide a tremendous surface area to recombine free electrons. The presence of tiny grains in PPDs thus raises the question of whether the magnetorotational instability (MRI) is able to drive rapid accretion consistent with observations. Charged tiny grains have similar conduction properties as ions, whose presence leads to qualitatively new behaviors in the conductivity tensor, characterized by n-bar /n{sub e}>1, where n{sub e} and n-bar denotemore »« less
https://doi.org/10.1088/0004-637X/739/1/51; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)
MAGNETOROTATIONAL-INSTABILITY-DRIVEN ACCRETION IN PROTOPLANETARY DISKS

Journal Article

Non-ideal MHD effects play an important role in the gas dynamics in protoplanetary disks (PPDs). This paper addresses the influence of non-ideal MHD effects on the magnetorotational instability (MRI) and angular momentum transport in PPDs using the most up-to-date results from numerical simulations. We perform chemistry calculations using a complex reaction network with standard prescriptions for X-ray and cosmic-ray ionizations. We first show that whether or not grains are included, the recombination time is at least one order of magnitude less than the orbital time within five disk scale heights, justifying the validity of local ionization equilibrium and strong couplingmore »« less
https://doi.org/10.1088/0004-637X/739/1/50; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)

Similar Records