The possibility of the laser effect in stellar atmospheres

The possibility of the existence population inversions in the atmospheres of hot (Be) stars is considered on the example of the 01 oxygen. The condition for self-excitation of a medium with a population inversion as a result of resonance scattering at the amplifying transition is found. The generation-line width due to the contribution of the spontaneous radiation is found for such a laser, which pertains to the class of lasers with nonresonant feedback. It is shown that the generation-line width may be significantly narrower than the gain-line width. Methods for the experimental observation of the laser effects in stellar atmospheres are considered.