A&A 480, 27-33 (2008)
Magnetic shear-driven instability and turbulent mixing in magnetized protostellar disksA. Bonanno1, 2 and V. Urpin1, 3
1 INAF - Osservatorio Astrofisico di Catania, via S. Sofia 78, 95123 Catania, Italy
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