Implication of Formation Mechanisms of HC5N in TMC-1 as Studied by 13C Isotopic Fractionation
Abstract
We observed the J = 9 - 8 and 16 - 15 rotational transitions of the normal species and five 13C isotopologues of HC5N to study its formation mechanisms toward the cyanopolyyne peak in Taurus Molecular Cloud-1, with the 45-m radio telescope of the Nobeyama Radio Observatory. We detected the five 13C isotopologues with high signal-to-noise ratios between 12 and 20, as well as the normal species. The abundance ratios of the five 13C isotopologues of HC5N are found to be 1.00:0.97:1.03:1.05:1.16 (±0.19) (1σ) for [H13CCCCCN]:[HC13CCCCN]:[HCC13CCCN]:[HCCC13CCN]:[HCCCC13CN]. We do not find any significant differences among the five {}13{{C}} isotopologues. The averaged [HC5N]/[13C isotopologues] abundance ratio is determined to be 94 ± 6 (1σ), which is slightly higher than the local interstellar elemental 12C/13C ratio of 60-70. Possible formation pathways are discussed on the basis of these results.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 2016
- DOI:
- 10.3847/0004-637X/817/2/147
- arXiv:
- arXiv:1512.05783
- Bibcode:
- 2016ApJ...817..147T
- Keywords:
-
- astrochemistry;
- ISM: individual objects: TMC-1;
- ISM: molecules;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- Accepted for publication in ApJ, 21 pages, 2 figures, 3 tables