Suprathermal rotation of interstellar grains
The mean rotational kinetic energy of an interstellar grain would be (3/2) kT/sub g/ if the grain, the gas, and any other parts of the system that couple to grain rotation were in equilibrium at temperature T/sub g/. In fact the grains are colder than the gas, and several processes characterized by different temperatures can excite grain rotation. Purely stochastic excitation leads to rotation characterized by some intermediate temperature. But a grain can be made to rotate suprathermally, that is, with an energy much greater than k times any temperature in the system. The torque that drives it can arise from accidental irregularities in the shape or surface characteristics of the grain. Three sources of residual unbalanced torque are examined: variation in accommodation coefficient, variation in photoelectric emissivity, and randomness in the distribution of surface sites where hydrogen molecule recombination is catalyzed.
- Research Organization:
- Lyman Laboratory, Harvard University
- OSTI ID:
- 5828634
- Journal Information:
- Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 231:2; ISSN ASJOA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANGULAR MOMENTUM
COSMIC GASES
CRYOGENIC FLUIDS
DISSIPATION FACTOR
ELASTICITY
ELEMENTARY PARTICLES
ELEMENTS
EMISSION
EMISSIVITY
FLUIDS
GASES
HYDROGEN
INTERSTELLAR GRAINS
INTERSTELLAR MAGNETIC FIELDS
MAGNETIC FIELDS
MASSLESS PARTICLES
MECHANICAL PROPERTIES
MOTION
NONMETALS
OPTICAL PROPERTIES
PARTICLES
PHOTOEMISSION
PHOTONS
PHYSICAL PROPERTIES
ROTATION
SECONDARY EMISSION
SURFACE PROPERTIES
TENSILE PROPERTIES
TORQUE