Ionization in atmospheres of brown dwarfs and extrasolar planets. I. The role of electron avalanche

Christiane Helling, M. Jardine, S. Witte, D. A. Diver

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)

Abstract

Brown dwarf and extrasolar planet atmospheres form clouds which strongly influence the local chemistry and physics. These clouds are globally neutral obeying dust-gas charge equilibrium which is, on short timescales, inconsistent with the observation of stochastic ionization events of the solar system planets. We argue that a significant volume of the clouds in brown dwarfs and extrasolar planets is susceptible to local discharge events. These are electron avalanches triggered by charged dust grains. Such intra-cloud discharges occur on timescales shorter than the time needed to neutralize the dust grains by collisional processes. An ensemble of discharges is likely to produce enough free charges to suggest a partial and stochastic coupling of the atmosphere to a large-scale magnetic field.

Original languageEnglish
Article number4
Number of pages6
JournalAstrophysical Journal
Volume727
Issue number1
DOIs
Publication statusPublished - 20 Jan 2011

Keywords

  • Brown dwarfs
  • Plasmas
  • Stars: atmospheres

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