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

Helling, C., Jardine, M., Witte, S. and Diver, D.A. (2011) Ionization in atmospheres of brown dwarfs and extrasolar planets. i. The role of electron avalanche. Astrophysical Journal, 727(1), p. 4. (doi: 10.1088/0004-637X/727/1/4)

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Publisher's URL: http://dx.doi.org/10.1088/0004-637X/727/1/4

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.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Diver, Professor Declan
Authors: Helling, C., Jardine, M., Witte, S., and Diver, D.A.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Astrophysical Journal
ISSN:0004-637X
Published Online:22 December 2010

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