Photon Dominated Region Modelling of Barnard 68
Abstract
A Photon-Dominated Region (PDR) model is presented for the line emission of the Barnard 68 dark globule. With a roughly spherical morphology and a previously determined density profile, Barnard 68 is an ideal test-bed for spherical PDR models in low-UV radiation fields. This allows the study of the impact of the chemistry in the predicted line emission. We compare the spherically symmetric PDR model by Störzer, Stutzki & Sternberg (1996) to observations of the 12CO J = 2→1 and J = 3→2 rotational transitions as well as the [CI] 3P1→3P0 fine structure transition. The analysis shows that Polycyclic Aromatic Hydrocarbons (PAH) have to be included in the chemical network of the PDR model in order to explain the observed [CI] and CO emission. The line intensity of the best-fit model reproduces the observations within ~30%. Additionally, predictions for the [CII] 2P3/2→2P1/2, [CI] 3P2→3P1, 12CO J = 5→4, and J = 4→3 transitions are presented. Observations of these transitions with future instruments (APEX, NANTEN2, HERSCHEL, SOFIA) will allow to test our PDR model of Barnard 68.
- Publication:
-
Astrochemistry: Recent Successes and Current Challenges
- Pub Date:
- 2005
- Bibcode:
- 2005IAUS..231P..90P
- Keywords:
-
- astrochemistry;
- ISM: globules;
- ISM: individual: Barnard 68;
- ISM: molecules