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Motion with velocities much larger than the characteristic local thermal (Maxwellian) velocity is called suprathermal or superthermal. Processes involving magnetic fields, such as solar flares, can produce suprathermal particle motions. In the case of interstellar dust grains, suprathermal rotation has been invoked as a process involved in the grain alignment that is responsible for polarizing transmitted radiation.
Although the term suprathermal could also in principle be applied to situations like astrophysical masers, where a group of atoms or molecules exists in a condition with more members in an excited energy state than in a linked lower energy state (thus providing a negative thermodynamic temperature and the possibility of stimulated emission of radiation), this use of the term has not been in common use.
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References and Further Reading
Whittet DCB (2003) Dust in the galactic environment, vol 2. Institute of Physics Publishing, Bristol
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© 2014 Springer-Verlag Berlin Heidelberg
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Irvine, W.M. (2014). Suprathermal. In: Amils, R., et al. Encyclopedia of Astrobiology. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-27833-4_1549-3
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DOI: https://doi.org/10.1007/978-3-642-27833-4_1549-3
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Publisher Name: Springer, Berlin, Heidelberg
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