Angular Momentum Transport in Protoplanetary Disks
Xue-Ning Bai
astro-ph.EP
Submitted: 2026-08-23
Updated: 2026-08-25
Comments: To appear in Annual Review of Astronomy and Astrophysics, Volume 64 (CC BY-NC-ND 4.0). This is the author's version (70 pages, 10 figures), which merges the supplement into the main document
Journal ref: Annual Review of Astronomy and Astrophysics, 2026, Vol. 64
DOI: 10.1146/annurev-astro-043024-115835
License: http://creativecommons.org/licenses/by/4.0/
The gist: We review our current understanding on the physical processes that govern angular momentum transport and evolution of protoplanetary disks.
Terminology
Abstract
We review our current understanding on the physical processes that govern angular momentum transport and evolution of protoplanetary disks. Extremely rich in physics, these processes are intimately connected to disk gas dynamics, with profound implications for planet formation. We organize them into a three-level hierarchical framework: (1) The coupling of gas with magnetic fields and radiation sets the microphysical foundation for understanding protoplanetary disk dynamics. Key ingredients include non-ideal magnetohydrodynamic effects (requiring ionization chemistry), along with heating and cooling processes. The disk can be divided into three radial sectors governed by distinct microphysics. (2) Protoplanetary disks host diverse gas dynamical processes, including hydrodynamic, magnetic and gravitational instabilities, along with thermally and magnetically-driven disk winds. Many of these individual processes are reasonably well understood, while others still require detailed investigation. (3) Protoplanetary disks are highly complex ecosystems where multiple processes interact. It is recognized that the bulk disk exhibits weak turbulence, with magnetically-driven wind likely serving as the primary transport mechanism. However, our knowledge remains highly limited regarding the disk's innermost region, early stages, long-term evolution, and environmental effects.
Sources
- ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT) VII: the layered molecular outflow from HL Tau and its relationship with the ringed disk
- Puffed-up Inner Rings and Razor-thin Outer Rings in Structured Protoplanetary Disks
- Photoevaporation Can Reproduce Extended $\mathrm{H_2}$ Emission from Protoplanetary Disks Imaged by JWST MIRI
- From thermal to magnetic driving: spectral diagnostics of simulation-based magnetothermal disc wind models
- Detailed radial scale height profile of dust grains as probed by dust self-scattering in HL Tau
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