The stability of magnetized protostellar disks with the Hall effect and buoyancy

Free access article

Issue		A&A Volume 437, Number 1, July I 2005


Page(s)		23 - 30
Section		Astrophysical processes
DOI		http://dx.doi.org/10.1051/0004-6361:20041897

A&A 437, 23-30 (2005)
DOI: 10.1051/0004-6361:20041897

The stability of magnetized protostellar disks with the Hall effect and buoyancy

V. Urpin^{1, 2} and G. Rüdiger¹

¹ Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
e-mail: gruediger@aip.de
² A. F. Ioffe Institute of Physics and Technology, 194021 St. Petersburg, Russia

(Received 25 August 2004 / Accepted 5 March 2005)

Abstract
The stability properties of cool protostellar disks are examined by use of the dispersion relation taking into account the Hall effect and buoyancy. Depending on the conditions, different types of instabilities can arise in different regions of the disk. In very low-ionized regions the instability associated with baroclinic effects of buoyancy is likely most efficient. The shear-Hall instability will be responsible for destabilization of regions with a weak magnetic field (parallel to the rotation axis) and with low conductivity ( ${\rm\Lambda}<a_{\rm e}$ , ${\rm\Lambda}=\sigma B^2/\rho\Omega$ Elsässer number, $a_{\rm e}$ magnetization parameter of electrons). The magnetorotational instability modified by buoyancy should be the main destabilizing factor in regions with sufficiently strong magnetic fields and/or high conductivity ( ${\rm\Lambda} > a_{\rm e}$ ). For a magnetic field amplitude of 1 Gauss the transition between both the regions happens at approximately 1 AU.

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

SIMBAD Objects in preparation

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.