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

By Xue-Ning Bai, James M. Stone. 2013

284 citations recorded by the source corpus.

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 β ∼ 105 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 ∼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.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/5955d309450270d404fe7a6940284452999eb901

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Instrumentation

In Statistical and Nonlinear Physics

Citations in the corpus

Global simulations of protoplanetary disks with net magnetic flux: I. Non-ideal MHD case (2016, result): “This is consistent with the shearing-box measurements of Bai & Stone (2013), regardless of the fast-magnetosonic point being crossed in the computational domain (see Sect.”
Global Simulations of the Inner Regions of Protoplanetary Disks with Comprehensive Disk Microphysics (2017, background): “Fiducially, we choose b = 100 5, appropriate for the inner region of PPDs (Bai 2013; Bai & Stone 2013), but we also consider stronger fields in Section 7.1.”
Astrophysics with Extraterrestrial Materials (2016, background): “Internal processes that might drive disk evolution include magnetorotational instability (MRI) (Balbus & Hawley 1991) and gravitational torques, each of which may operate in protoplanetary disks so long as certain conditions are met (Armitage 2011, Bai 2011, Bai & Stone 2013).”
On the diversity and statistical properties of protostellar discs (2018, background): “Recent studies have suggested that accretion in protostellar discs may be driven by the loss of angular momentum in disc winds rather than by angular momentum transport within the disc itself (Bai & Stone 2013; Simon et al. 2013; Suzuki et al. 2016; Wang & Goodman 2017; Rafikov 2017).”
Gaps, Rings, and Non-Axisymmetric Structures in Protoplanetary Disks - From Simulations to ALMA Observations (2014, background): “Recent simulations that included ambipolar diffusion (Bai & Stone 2013) and Hall diffusion (Lesur et al. 2014; Bai 2014) showed a strong laminar stress depending on the field geometry.”
Thanatology in protoplanetary discs - The combined influence of Ohmic, Hall, and ambipolar diffusion on dead zones (2014, methodology): “To circumvent this problem, we following Bai & Stone (2013b) by introducing a capping procedure on the magnetic diffusivities ηO,H,A.”
GLOBAL SIMULATIONS OF PROTOPLANETARY DISKS WITH OHMIC RESISTIVITY AND AMBIPOLAR DIFFUSION (2015, methodology): “These are the first quasi-global simulations to be conducted of PPDs that are threaded by vertical magnetic fields and which include this combination of non ideal MHD effects, and as such are most comparable with the shearing box simulations presented by Bai & Stone (2013), hereafter BS13.”