The formation of interstellar molecular lines in a turbulent velocity field with finite correlation length. II.
Abstract
We investigated the formation of interstellar molecular lines in a turbulent velocity field with finite correlation length, extending previous work (Albrecht and Kegel, 1987) to the regime sigma much greater than V(therm). For this we transformed the generalized transfer equation by introducing a new, Delta(nu)dependent velocity coordinate the origin of which corresponds to the center of the profile of the absorption coefficient. This transformation allows in the case of sigma much greater than V(therm) to reduce the numerical effort considerably. We give numerical results for NLTEcalculations for a 10level CO molecule for (sigma/v(therm)) = 20 as well as for comparison for sigma = v(therm). Our results show that a finite correlation length affects strongly the line profiles, the line width, and the intensity ratios. At low densities also the excitation conditions are effected, i.e., the NLTEeffects are modified. These effects increase with inceasing ratio sigma/v(therm).
 Publication:

Astronomy and Astrophysics
 Pub Date:
 March 1993
 Bibcode:
 1993A&A...270..407K
 Keywords:

 Carbon Monoxide;
 Interstellar Radiation;
 Line Spectra;
 Magnetohydrodynamic Turbulence;
 Molecular Spectra;
 Carbon 12;
 Carbon 13;
 Mixing Ratios;
 Nonequilibrium Thermodynamics;
 Astrophysics