Stability of an axisymmetric massive current sheet supported by a potential magnetic field.
Abstract
The ideal linear stability of a class of axisymmetric magnetostatic equilibria is investigated by using the classical energy principle of Bernstein et al. (1958). The system under consideration is constituted of an infinitely thin equatorial disk of cold dense matter and of a corona filled up with a massless plasma. The disk is supported against the radial gravity of a central object by a magnetic field which is potential in the corona and has its footpoints firmly anchored in the rigid boundary of that region (line-tying). Such a configuration is proven to be always stable with respect to axisymmetric perturbations, but to be stable against arbitrary ones if and only if two criteria (in which stabilization by line-tying appears explicitly) are satisfied. These criteria are applied to several particular equilibria (constructed by a general superposition method), which may be considered as crude models useful to understand some of the mechanisms at work in solar prominences and in accretion disks around compact objects. Stable configurations are shown to exist in each of the cases which have been worked out.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- February 1996
- Bibcode:
- 1996A&A...306..645L
- Keywords:
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- MHD;
- PLASMAS;
- SUN: PROMINENCES;
- ACCRETION DISKS;
- INSTABILITIES