Issue |
A&A
Volume 645, January 2021
|
|
---|---|---|
Article Number | L9 | |
Number of page(s) | 6 | |
Section | Letters to the Editor | |
DOI | https://doi.org/10.1051/0004-6361/202040031 | |
Published online | 18 January 2021 |
Letter to the Editor
A “no-drift” runaway pile-up of pebbles in protoplanetary disks in which midplane turbulence increases with radius
1
ISAS/JAXA, Sagamihara, Kanagawa, Japan
e-mail: hyodo@elsi.jp
2
Earth-Life Science Institute, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8550, Japan
3
Laboratoire J.-L. Lagrange, Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, 06304 Nice, France
Received:
1
December
2020
Accepted:
22
December
2020
Context. A notable challenge of planet formation is to find a path to directly form planetesimals from small particles.
Aims. We aim to understand how drifting pebbles pile up in a protoplanetary disk with a nonuniform turbulence structure.
Methods. We consider a disk structure in which the midplane turbulence viscosity increases with the radius in protoplanetary disks, such as in the outer region of a dead zone. We perform 1D diffusion-advection simulations of pebbles that include back-reaction (the inertia) to the radial drift and the vertical and radial diffusions of pebbles for a given pebble-to-gas mass flux.
Results. We report a new mechanism, the “no-drift” runaway pile-up, that leads to a runaway accumulation of pebbles in disks, thus favoring the formation of planetesimals by streaming and/or gravitational instabilities. This occurs when pebbles drifting in from the outer disk and entering a dead zone experience a decrease in vertical turbulence. The scale height of the pebble subdisk then decreases, and, for small enough values of the turbulence in the dead zone and high values of the pebble-to-gas flux ratio, the back-reaction of pebbles on gas leads to a significant decrease in their drift velocity and thus their progressive accumulation. This occurs when the ratio of the flux of pebbles to that of the gas is large enough that the effect dominates over any Kelvin-Helmholtz shear instability. This process is independent of the existence of a pressure bump.
Key words: accretion, accretion disks / planets and satellites: formation / planet-disk interactions
© ESO 2021
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.