### Turbulent convection in accretion discs

Lesur, G *(Cambridge)*

Monday 17 August 2009, 15:30-15:50

Meeting Room 2, CMS

#### Abstract

Transport of angular momentum has always been a central problem of accretion disc theory. Since the discovery of the magnetorotational instability in accretion discs by Balbus and Hawley (1991), MRI-driven turbulence is believed to be the best candidate to explain anomalous transport in discs.
Despite this result, several other routes to turbulence have been considered over the last two decades, with limited success. A possible alternative to MRI turbulence is turbulent convection, driven by an unstable vertical entropy gradient in the disc. Several studies have shown that convection was actually transporting angular momentum inward, and is therefore not favourable to accretion.
In this presentation, I will revisit the problem of turbulent convection in accretion discs, using modern numerical methods. In particular, I will show that this hydrodynamic process could actually drive outward angular momentum transport if certain conditions are met, with an efficiency compatible with protoplanetary discs observations.

#### Presentation