Observations of quasi-thermal and maser phenomena in rotationally excited OH. I.
Abstract
Absorption features arising from Lambda-doublet transitions in a very short-lived rotationally excited state of OH have been discovered in the direction of the W3 continuum peak. Analyses of these features and of broad emission features in Sgr B2 indicate the presence of massive regions with very high densities. An extensive search for new sources of maser emission from excited-state OH has resulted in the detection of maser features in NGC 7538, OH 69.5 - 1.0, M17, W51, and Orion (OH). Observations with circular polarization suggest Zeeman effects in some spectra, with inferred magnetic field strengths of several milligauss. A rapid time variation has been observed in the maser spectrum of Sgr B2, and evidence is presented for variations in W51 and W3 (continuum).
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 1975
- DOI:
- 10.1086/153755
- Bibcode:
- 1975ApJ...200....6R
- Keywords:
-
- Absorption Spectra;
- Hydroxyl Emission;
- Interstellar Masers;
- Interstellar Radiation;
- Molecular Excitation;
- Molecular Rotation;
- Electron Transitions;
- Fine Structure;
- Infrared Astronomy;
- Interstellar Extinction;
- Astrophysics