Chemical evolution in collapsing cores
Abstract
We study the chemical evolution in the central core of contracting interstellar clouds. The chemical rate equations and the hydrodynamic equations are integrated simultaneously. The contraction is followed from very low density (n=10 cm^-3) to a high-density core with n>10^7 cm^-3. The chemical evolution is studied for various physical and chemical conditions, including the effects of varying the cosmic ray ionization rate, in order to understand the observed structures in TMC-1 and the extended ridge cloud in Orion. Our results give good agreement with the observations for models with fast ion-dipole reaction rates, low cosmic ray ionization rates and low depletion of N and S. It is also found that there should be different stages of evolution with different densities in these sources.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- December 1997
- DOI:
- 10.1093/mnras/292.3.481
- Bibcode:
- 1997MNRAS.292..481E
- Keywords:
-
- Interstellar Chemistry;
- Chemical Evolution;
- Molecular Clouds;
- Hydrodynamic Equations;
- Ion Production Rates;
- Reaction Kinetics;
- Cosmic Rays;
- Astronomical Models;
- Astrophysics;
- HYDRODYNAMICS;
- MOLECULAR PROCESSES;
- ISM: ABUNDANCES;
- ISM: CLOUDS;
- COSMIC RAYS;
- ISM: MOLECULES