Observations of interstellar CH at 9 cm wavelength.
Abstract
The 9-cm ground-state lines of CH have been observed in southern galactic sources, mainly HII regions. The F = 0-1 transition at 3264 MHz has been detected in emission in 16 sources; the F = 1-1 transition at 3335 MHz has been seen in absorption in 5 sources and in emission in 2 others. Where the F = 1-1 transition is in absorption, the transition temperature is positive and below about 100 K. The F = 0-1 transition is generally inverted, with a transition temperature between - 10 and 0 K. The column densities of CH are in the vicinity of 10 to the 14th power per sq cm, slightly below those for OH but many times those for H2CO. There is no correlation between apparent optical depths of CH and those for OH or H2CO absorption. There is also no enhancement of CH in the dense molecular clouds near the center of the Galaxy.
- Publication:
-
Australian Journal of Physics
- Pub Date:
- June 1976
- DOI:
- 10.1071/PH760211
- Bibcode:
- 1976AuJPh..29..211G
- Keywords:
-
- Interstellar Gas;
- Microwave Emission;
- Molecular Spectra;
- Radio Astronomy;
- Formaldehyde;
- Free Radicals;
- H Ii Regions;
- Hydroxyl Emission;
- Astrophysics