Gravitational stability of a cylindrical plasma with an azimuthal and an axial magnetic field

J. A. McLeman, C. H. -T. Wang, R. Bingham

Research output: Contribution to journalArticle


We consider the gravitational stability of a current-carrying filamentary cloud in the presence of both axial and azimuthal magnetic fields using a simple analytic model. The azimuthal magnetic field is shown to give rise to a new contribution, dictated by Ampere's law, in the corresponding virial equation for magnetohydrodynamic equilibrium. From this we obtain a computationally inexpensive guidance on the gravitational stability of current-carrying filamentary clouds. The approach not only provides a fresh insight into the essential physical mechanisms involved but also demonstrates clearly that, for sufficiently large and yet astronomically realistic currents, the azimuthal magnetic field can cause filamentary clouds to undergo instability.

Original languageEnglish
Article number105
Number of pages5
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 10 Sep 2012


  • magnetic fields
  • star formation
  • plasma

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