Astron. Astrophys. 355, 1181-1190 (2000)

Nonstationary magnetorotational processes in a rotating magnetized cloud

N.V. Ardeljan ¹, G.S. Bisnovatyi-Kogan ² and S.G. Moiseenko <sup>2

1</sup> Department of Computational Mathematics and Cybernetics, Moscow State University, Vorobjevy Gory, Moscow B-234 119899, Russia (ardel@redsun.cs.msu.su)
² Space Research Institute, Profsoyuznaya 84/32, Moscow 117810, Russia (gkogan@mx.iki.rssi.ru; moiseenko@mx.iki.rssi.ru)

Received 19 July 1999 / Accepted 3 December 1999

Abstract

We perform 2D numerical simulations of a magnetorotational explosion of a rotating magnetized gas cloud. We found that amplification of a toroidal magnetic field due to the differential rotation leads to a transformation of the part of the rotational energy of the cloud to the radial kinetic energy. Simulations have been made for 3 initial values of (the relation of magnetic energy to the gravitational energy of the cloud): . Part of the matter - of the mass of the cloud ( of the final gravitational energy of the cloud) - gets radial kinetic energy which is larger than its potential energy and can be thrown away to the infinity. It carries about 30% of the initial angular momentum of the cloud. This effect is important for angular momentum loss in the processes of stellar formation, and for the magnetorotational mechanism of explosion suggested for supernovae. Simulations have been made on the basis of the Lagrangian 2D numerical implicit scheme on a triangular grid with grid reconstruction.

Key words: Magnetohydrodynamics (MHD) stars: evolution stars: supernovae: general

Send offprint requests to: S.G. Moiseenko (moiseenko@mx.iki.rssi.ru)

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Contents

• 1. Introduction
• 2. Basic equations
• 3. Collapse of a rotating magnetized gas cloud
  • 3.1. Formulation of the problem
  • 3.2. Initial magnetic field configuration
• 4. Results
• 5. Discussion
• Appendices
  • A: numerical method
    • A.1. Calculation of the initial and boundary values of the magnetic field
    • A.2. Testing
• Acknowledgements
• References

© European Southern Observatory (ESO) 2000

Online publication: March 21, 2000
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