Buoyancy instabilities in degenerate, collisional, magnetized plasmas

Philip Chang, Eliot Quataert

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

In low-collisionality plasmas, anisotropic heat conduction due to a magnetic field leads to buoyancy instabilities for any non-zero temperature gradient.We study analogous instabilities in degenerate collisional plasmas, i.e. when the electron collision frequency is large compared to the electron cyclotron frequency. Although heat conduction is nearly isotropic in this limit, the small residual anisotropy ensures that collisional degenerate plasmas are also convectively unstable independent of the sign of the temperature gradient. We show that the range of wavelengths that are unstable is independent of the magnetic field strength, while the growth time increases with decreasing magnetic field strength. We discuss the application of these collisional buoyancy instabilities to white dwarfs and neutron stars. Magnetic tension and the low specific heat of a degenerate plasma significantly limit their effectiveness; the most promising venues for growth are in the liquid oceans of young, weakly magnetized neutron stars (B ≲ 109 G) and in the cores of young, high magnetic field white dwarfs (B ~ 109 G).

Original languageEnglish (US)
Pages (from-to)246-252
Number of pages7
JournalMonthly Notices of the Royal Astronomical Society
Volume403
Issue number1
DOIs
StatePublished - Mar 2010
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Convection
  • Instabilities
  • Neutron
  • Plasmas
  • Stars
  • White dwarfs

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