Observation of C8H- toward IRC+10216
Abstract
Five rotational lines of the C8H- ion were observed in the circumstellar envelope of IRC +10216 with the Nobeyama 45m telescope. An improved value of the column density of the C8H radical yielded a [C8H-] frasl [C8H] ratio of 37% - nearly 4 times larger than the [C6H-] frasl [C6H] ratio (8.6%) and nearly 1500 times the [C4H-] frasl [C4H] ratio (0.024%), which may indicate more efficient formation of longer carbon chain anions. The excitation temperature of C8H- (16±2K) derived here is somewhat lower than that of the two smaller anions C6H- (32K) and C4H- (23K) in IRC +10216.
- Publication:
-
Publications of the Astronomical Society of Japan
- Pub Date:
- October 2007
- DOI:
- 10.1093/pasj/59.5.L47
- Bibcode:
- 2007PASJ...59L..47K
- Keywords:
-
- ISM: molecules;
- molecular processes;
- radio lines: stars;
- stars: circumstellar matter;
- stars: individual (IRC +10216)