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Alignment of dust grains in ionized regionsThe rate at which charged dust grains in a plasma are torqued by passing ions and electrons is calculated. When photo-emission of electrons is not important, attraction of ions by the grain monopole potential increases the rate at which the grains' spins are dealigned by nearly an order of magnitude. Consequently, the energy density of the magnetic field required to align grains in an H II region may be increased by about an order of magnitude. In contrast, electric dipole and quadrupole moments are unlikely to produce large dealignment rates for grains of modest length-to-width ratio. Nonetheless, for positively charged grains these higher-order moments likely prevent monopole repulsion of ions from reducing the dealignment rate far below that for neutral grains. The presence of positive grain charge therefore does not greatly facilitate grain alignment in an H II region.
Document ID
19940036472
Document Type
Reprint (Version printed in journal)
Authors
Anderson, Nels (Max-Planck-Inst. fuer Extraterrestrische Physik, Garching, Germany; Illinois Univ. Urbana, United States)
Watson, William D. (Illinois Univ. Urbana, United States)
Date Acquired
August 16, 2013
Publication Date
March 1, 1993
Publication Information
Publication: Astronomy and Astrophysics
Volume: 270
Issue: 2-Jan
ISSN: 0004-6361
Subject Category
ASTROPHYSICS
Funding Number(s)
CONTRACT_GRANT: NSF AST-89-19614
CONTRACT_GRANT: NAGW-1104
Distribution Limits
Public
Copyright
Other