EDP Sciences
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Volume 480, Number 1, March II 2008
Page(s) 27 - 33
Section Astrophysical processes
DOI http://dx.doi.org/10.1051/0004-6361:20077562

A&A 480, 27-33 (2008)
DOI: 10.1051/0004-6361:20077562

Magnetic shear-driven instability and turbulent mixing in magnetized protostellar disks

A. Bonanno1, 2 and V. Urpin1, 3

1  INAF - Osservatorio Astrofisico di Catania, via S. Sofia 78, 95123 Catania, Italy
    e-mail: abo@oact.inaf.it
2  INFN, Sezione di Catania, via S. Sofia 72, 95123 Catania, Italy
3  A.F. Ioffe Institute of Physics and Technology and Isaac Newton Institute of Chile, Branch in St. Petersburg, 194021 St. Petersburg, Russia

(Received 28 March 2007 / Accepted 5 December 2007)

Context.Observations of protostellar disks indicate the presence of the magnetic field of thermal (or superthermal) strength. In such a strong magnetic field, many MHD instabilities responsible for turbulent transport of the angular momentum are suppressed.
Aims.We consider the shear-driven instability that can occur in protostellar disks even if the field is superthermal.
Methods.This instability is caused by the combined influence of shear and compressibility in a magnetized gas and can be an efficient mechanism to generate turbulence in disks.
Results.The typical growth time is of the order of several rotation periods.

Key words: accretion, accretion disks -- magnetohydrodynamics (MHD) -- instabilities -- turbulence -- stars: formation

© ESO 2008