Modeling Radiative Transfer in Molecular Clouds. I. HCO + in the Star-forming Region W49A North
Abstract
A new general multilevel, non-Local Thermodynamic Equilibrium (LTE) radiative transfer code, valid for any velocity field, is applied to HCO(+) observations of W49A North. Three classes of collapse models are considered: free-fall collapse (v proportional to 1/sq. root of r), rho proportional to r-3/2 throughout the molecular cloud, successfully reproduces the features of the observations and gives the best fit to the J = 1-0 and J = 3-2 profiles both toward the prominent H II component G of W49A North and off the center. In addition to a slow radial fall-off of density, the theoretical modeling implies the following for the molecular cloud: the large line widths result from motions occurring within the inner 1 pc, and there are probably one or more fragments with peculiar velocities within this same region.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 1994
- DOI:
- 10.1086/174991
- Bibcode:
- 1994ApJ...437..222D
- Keywords:
-
- Astronomical Models;
- Formyl Ions;
- H Ii Regions;
- Interstellar Matter;
- Molecular Clouds;
- Radiative Transfer;
- Star Formation;
- Computerized Simulation;
- Mathematical Models;
- Astrophysics;
- ISM: H II REGIONS;
- ISM: CLOUDS;
- ISM: INDIVIDUAL ALPHANUMERIC: W49;
- ISM: MOLECULES;
- RADIATIVE TRANSFER