Detection of the 2 20 2 21 Transition of HDO in Orion A: Evidence for Dense Clumped Gas in the Hot Core
Abstract
The first astronomical detection of the 10.3 GHz, 220 → 221, transition of the molecule HDO is reported. Two components of OMC-1 are identified: the "hot core", and the "spike" component (identified with the "compact molecular ridge cloud". The best-fit parameters in a statistical equilibrium model of the hot core are an effective radiation temperature of Trad ≡ 350K and a density of n(H2) ≡ 3×109cm-3. The best-fit parameters for the spike component are Trad ≡ 40K and n(H2) ≡ 3×106cm-3. The observations indicate an abundance ratio of [HDO]/[H2O] ≡ 10-3 in the hot core.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 1988
- DOI:
- 10.1086/166099
- Bibcode:
- 1988ApJ...326..376P
- Keywords:
-
- Electron Transitions;
- Heavy Water;
- Interstellar Gas;
- Molecular Clouds;
- Orion Nebula;
- Brightness Temperature;
- Molecular Energy Levels;
- Virial Theorem;
- Water Masers;
- Astrophysics;
- INTERSTELLAR: ABUNDANCES;
- INTERSTELLAR: MOLECULES;
- NEBULAE: ORION NEBULA