Observations of Cyclopropenylidene (Cyclic-C3H2) in the External Galaxies NGC 253 and M 82
Abstract
Several transitions of the cyclopropenylidene (cyclic-C3H2) molecule have been observed in the 83-218GHz region toward NGC 253 and M 82. Assuming local thermodynamic equilibrium, the rotational temperatures were determined to be 10.8 ± 2.4 K and 11.5 ± 3.0 K for NGC 253 and M 82, respectively, where the errors indicate three standard deviations (3 σ). The column densities of cyclic-C3H2 were determined to be N(NGC 253) = (2.7 ± 1.1) × 1013 cm-2. and N(M 82) = (1.9 ± 0.9) × 1013 cm-2. Large velocity gradient calculations were applied to estimate kinetic temperatures of around 60K for NGC 253 and M 82. Considering the present result and recent observations of NH3 in both galaxies, molecular production mechanisms are discussed.
- Publication:
-
Publications of the Astronomical Society of Japan
- Pub Date:
- June 2004
- DOI:
- 10.1093/pasj/56.3.431
- Bibcode:
- 2004PASJ...56..431O
- Keywords:
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- galaxies: individual (NGC 253;
- M 82);
- galaxies: starburst;
- ISM: molecules;
- molecular processes;
- radio lines: galaxies