First Astronomical Detection of the Cumulene Carbon Chain Molecule H2C6 in TMC-1
Abstract
The cumulene carbenes are important components of hydrocarbon chemistry in low-mass star-forming cores. Here we report the first astronomical detection of the long-chain cumulene carbene H2C6 in the interstellar cloud TMC-1, from observations of two of its rotational transitions: JK,K' = 71,7 --> 61,6 at 18.8 GHz and 81,8 --> 71,7 at 21.5 GHz, using NASA's Deep Space Network 70 m antenna at Goldstone, California. In addition we also observed the shorter cumulene carbene H2C4 at the same position. The fractional abundance of H2C6 relative to H2 is about 4.7 × 10-11 and that of H2C4 is about 1.1 × 10-9. The abundance of H2C6 is in fairly good agreement with gas-phase chemical models for young molecular cloud cores, but the abundance of H2C4 is significantly larger than predicted.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 1997
- DOI:
- 10.1086/310622
- arXiv:
- arXiv:astro-ph/9702183
- Bibcode:
- 1997ApJ...480L..63L
- Keywords:
-
- INTERSTELLAR: MOLECULES;
- LINE: IDENTIFICATION;
- MOLECULAR PROCESSES;
- RADIO LINES: GENERAL;
- STARS: FORMATION;
- interstellar: molecules;
- Line: Identification;
- Molecular Processes;
- radio lines;
- Stars: Formation;
- Astrophysics
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