4–8 Aug 2014
Niels Bohr Institute
Europe/Copenhagen timezone

Thanatology in protoplanetary discs

5 Aug 2014, 11:00
30m
Auditorium A (Niels Bohr Institute)

Auditorium A

Niels Bohr Institute

Blegdamsvej 17 Copenhagen
Workshop Main Programme Tuesday Morning

Speaker

Dr Geoffroy Lesur (CNRS/IPAG)

Description

The existence of magnetically driven turbulence in protoplanetary discs has been a central question since the discovery of the magnetorotational instability (MRI). Early models considered Ohmic diffusion only and led to a scenario of layered accretion, in which a magnetically ``dead'' zone in the disc midplane is embedded within magnetically ``active'' surface layers at distances of about 1--10 au from the central protostellar object. Recent work has suggested that a combination of Ohmic dissipation and ambipolar diffusion can render both the midplane and surface layers of the disc inactive and that torques due to magnetically driven outflows are required to explain the observed accretion rates. In this talk, I will present recent results revisiting this problem including all three non-ideal MHD effects: Ohmic diffusion, Ambipolar diffusion and the Hall effect. I will show in particular that the Hall effect can ``revive'' dead zones by providing a large scale magnetic torque in the disc midplane, potentially leading to significant accretion rates. Implications for the global evolution of protoplanetary discs will be discussed.

Primary author

Dr Geoffroy Lesur (CNRS/IPAG)

Co-authors

Dr Matthew Kunz (Princeton University) Dr Sébastien Fromang (Irfu/CEA Saclay)

Presentation materials