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The MPIA conference series
at Ringberg Castle
The MPIA conference series
at Ringberg Castle
EPoS 2020 Suggested Contribution
Is disk accretion driven by MHD disk winds?

Benoit Tabone
Leiden U, Leiden, NL
The extraction of angular momentum in disks remains an open question. Recent MHD numerical simulations including non-ideal effects, together with new constraints on the level of turbulence in disks suggest that magnetic outflows launched from the disk surface ("MHD disk-winds") are required to extract angular momentum and drive accretion. If present in the protostellar phase, MHD disk-winds could regulate disk formation, limit core-to-star efficiency, and modify the structure of protostellar disks. However, their existence remains highly debated. The unique combination of sensitivity and angular resolution offered by ALMA and the future JWST is now allowing us to conduct stringent tests on the presence of MHD disk-winds and quantify their impact on star and planet formation. In this contribution, we present our effort to unveil MHD disk-winds in protostars by combining ALMA observations, astrochemical modelling and numerical simulations. We review an ALMA study of the protostellar system HH212 down to 16au scales that provides the most stringent observational test of MHD disk-winds to date. Comparison with stationary wind models suggests that in this system, an MHD disk-wind extracts most of the angular momentum required to drive disk accretion and limits the core-to-star efficiency to ~50%. We also discuss new independent tests based on the thermochemistry and on the morphology of the perturbations imprinted by the passage of bow-shocks in slow disk-winds.
Caption: a) Original SO2 maps of the slow rotating flow unveiled by ALMA in HH212 at 45 au resolution. Position-velocity cuts across the flow (not shown here) down to 16 au resolution are reproduced by an MHD disk-wind model launched from out to the outer edge of the disk. b) Poloidal snapshot of an hydrodynamic simulation showing the large scale interaction between a fast jet and a slow disk-wind. c) Poloidal maps of the temperature computed from detailed thermochemical models of MHD disk-winds. The thermal and chemical structure depends markedly on the wind parameters.
S. Cabrit, LERMA, FR
J. Ferreira, IPAG, FR
G. Pineau des Forets, LERMA, FR
C. Codella, INAF, IT
E. van Dishoeck, LU, NL
Key publication

Suggested Session: Cores2Disks