English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

Observations suggest that protoplanetary disks have moderate accretion ratesonto the central young star, especially at early stages (e.g. HL Tau),indicating moderate disk turbulence. However, recent ALMA observations suggestthat dust is highly settled, implying weak turbulence. Motivated by suchtension, we carry out 3D stratified local simulations of self-gravitatingdisks, focusing on settling of dust particles in actively accreting disks. Wefind that gravitationally unstable disks can have moderately high accretionrates while maintaining a relatively thin dust disk for two reasons. First,accretion stress from the self-gravitating spirals (self-gravity stress) can bestronger than the stress from turbulence (Reynolds stress) by a factor of 5-20.Second, the strong gravity from the gas to the dust decreases the dust scaleheight by another factor of $\sim 2$. Furthermore, the turbulence is slightlyanisotropic, producing a larger Reynolds stress than the vertical dustdiffusion coefficient. Thus, gravitoturbulent disks have unusually highvertical Schmidt numbers ($Sc_z$) if we scale the total accretion stress withthe vertical diffusion coefficient (e.g. $Sc_z\sim$ 10-100). The reduction ofthe dust scale height by the gas gravity, should also operate ingravitationally stable disks ($Q>$1). Gravitational forces between particlesbecome more relevant for the concentration of intermediate dust sizes, formingdense clouds of dust. After comparing with HL Tau observations, our resultssuggest that self-gravity and gravity among different disk components could becrucial for solving the conflict between the protoplanetary disk accretion anddust settling, at least at the early stages.

Particle Dynamics in 3D Self-gravitating Disks II: Strong Gas Accretion and Thin Dust Disks