Molecules in external galaxies : the detection of CN, C2H and HNC andthe tentative detection of HC3N.
Abstract
: The detection of CN, C_2_H, and HNC and possibly also of HC_3_N is reported for the first time from extragalactic sources. The N=1-0 and 2-1 lines of CN were observed toward NGC 253, IC 342, and M82. Excitation temperatures (8-25K) and spatial extent (<700pc in most cases) are determined. CN N=2-1 emission is seen on opposite sides of the nucleus of M82. It may hence have a spatial distribution similar to that of CO and ^13^CO while the CS J=2-1 emission, which requires higher densities, is concentrated on the western side, C_2_H is detected toward M82, HNC toward IC 342, while HC_3_N may have been observed toward IC 342 and/or M82. Relative abundances are "normal" for CN, but seem to be larger than in galactic sources for the other molecules. Possible reasons for this are discussed.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- July 1988
- Bibcode:
- 1988A&A...201L..23H
- Keywords:
-
- Galactic Nuclei;
- Gas Density;
- Irregular Galaxies;
- Milky Way Galaxy;
- Molecular Clouds;
- Abundance;
- Carbon;
- Emission Spectra;
- Hydrogen;
- Nitrogen;
- Astrophysics