Theoretical Models of Photodissociation Fronts
Abstract
Observations of H2 line emission have revealed higher-than-expected gas temperatures in a number of photodissociation fronts. We discuss the heating and cooling processes in photodissociation regions. Observations of NGC 2023 are compared to a theoretical model in which there is substantial gas at temperatures T = 500-1000K heated by photoelectric emission and collisional deexcitation of H2. In general the model successfully reproduces the observed H2 line emission from a wide range of energy levels. The observed [SiII]34.8um emission appears to indicate substantial depletion of Si in NGC 2023.
- Publication:
-
Molecular Hydrogen in Space
- Pub Date:
- 2000
- DOI:
- 10.48550/arXiv.astro-ph/0008149
- arXiv:
- arXiv:astro-ph/0008149
- Bibcode:
- 2000mhs..conf..131D
- Keywords:
-
- Astrophysics
- E-Print:
- 8 pages, 6 figures, uses cupconf.sty and psfig.sty. To appear in H2 in Space, ed. F. Combes &