stars,[69] are also somewhat hazy under even the finest laboratory conditions,[70] and probably arise in regions of very low pressure in the stellar atmosphere.
(c) Widths of lines.—The width of an absorption line, produced by “Rayleigh Scattering” close to resonance conditions, is given by Stewart[71] as
where
is the observed width of the line,
the wave-length expressed in the same units, and
the number of molecules per square centimeter column in the line of sight.