An Etymological Dictionary of Astronomy and Astrophysics

A type of → interstellar dust grains with a size ranging from 150 to 1000 Å. Big grains consist of graphite and silicates. They
are in → thermal equilibrium with the radiation field and their emission can be described by a modified → blackbody radiation following from → Kirchhoff’s law.

See also: → big; → grain.