The main source of resistance to the flow of radiant energy in very hot gases, i.e. those with temperatures above 106 K. This opacity is due to free electrons, which do not absorb radiation but scatter it, thus increasing the time the radiation takes to pass through the gas. It is the main source of opacity in stars with masses greater than the Sun's. In less massive stars, the Kramers opacity is more important.
Subjects: Astronomy and Astrophysics.