Ammonia and cyanotriacetylene in the envelopes of CRL 2688 and IRC +10216.
Abstract
The first detection of the NH3 (1, 1) and (2, 2) inversion lines, and the rotational transition J = 21-20 of HC7N in the Egg nebula (CRL 2688) is reported. These lines have been reobserved in the envelope of IRC +10216, and the detection of the NH3 (2, 2) line which is centered approximately at the same velocity as the NH3 (1, 1) line has been confirmed. The ammonia lines detected in CRL 2688 are at least two times stronger than those observed in IRC +10216, while the HC7N line is about two times weaker, reflecting the difference in chemical processes operating in the two objects. The blueshifted wing in the HC7N spectrum of IRC +10216 is weaker than the redshifted wing, suggesting that self-absorption occurs in the circumstellar shell. The data have been interpreted in terms of a radiative transfer model, from which the source size, and the molecular abundance have been derived.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- September 1984
- Bibcode:
- 1984A&A...138L...5N
- Keywords:
-
- Acetylene;
- Ammonia;
- Cyano Compounds;
- Interstellar Gas;
- Line Spectra;
- Molecular Absorption;
- Astronomical Spectroscopy;
- Carbon Stars;
- Infrared Absorption;
- Nebulae;
- Red Shift;
- Self Absorption;
- Astrophysics