Modeling Line Profiles of Protostellar Collapse in B335 with the Monte Carlo Method

Abstract

A collapsing dark cloud core, B335, is modeled as an inside-out collapse. The radiative transfer code uses the Monte Carlo method and new collision rates for CS. Line profiles for several observed transitions of CS and H<SUB>2</SUB>CO are computed. We confirm that a double-peaked spectrum with a stronger blue peak is a good qualitative signature of infall. Compared to the models using the large velocity gradient method by Zhou et al., our best-fit model using the Monte Carlo method has 20% smaller infall radius, 70% larger CS abundance, and 30% larger H<SUB>2</SUB>CO abundance. Also, infall radii found from CS and H<SUB>2</SUB>CO agree better than they did in the modeling by Zhou et al. Our model also produces off-center spectra close to the observations.