Time Dependent Radiative Transfer. Damping of a Temperature Fluctuation. II. The two level Atom Case. Applications to the Interstellar Medium
Abstract
We study the radiative damping of harmonic temperature fluctuations by means of monochromatic radiation in an infillite homogeneous gas in L.T.E. If the gas is optically thick in the line, the relaxation time tB is of a diffusive type: t1L T2 X ta. The mean time ta between two consecutive scatterings of the photons is the sum of (i) the mean time of flight and (ii) the mean time of "capture" of the photons. Th order to flnd out the time of capture, we solve simultaneously the transfer equation and the equations of statistical equffibrium. Preliminary results show that in interstellar clouds the time of capture can be much longer than the time of flight. Key words: radiative transfer  interstellar matter
 Publication:

Astronomy and Astrophysics
 Pub Date:
 February 1972
 Bibcode:
 1972A&A....16..356L