An Etymological Dictionary of Astronomy and Astrophysics

A model of the internal structure of → massive stars in which a → convective core is surrounded by a large → radiative envelope. However, recent studies point to
the presence of a thin → convection zone in
the outer envelope of hot massive stars, beneath the → photosphere, which is caused by opacity peaks associated with iron and helium ionization. See also → iron convection zone.

See also: After Thomas Cowling (1906-1990), a British astronomer, who put forward the model; → model.