{sup 13}C Isotopic Fractionation of HC{sub 3}N in Two Starless Cores: L1521B and L134N (L183)

Journal Article · Fri Sep 01 04:00:00 EDT 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/AA82BA· OSTI ID:22875863

Taniguchi, Kotomi; Saito, Masao ^[1]; Ozeki, Hiroyuki ^[2]

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1. Department of Astronomical Science, School of Physical Science, SOKENDAI (The Graduate University for Advanced Studies), Osawa, Mitaka, Tokyo 181-8588 (Japan)
2. Department of Environmental Science, Faculty of Science, Toho University, Miyama, Funabashi, Chiba 274-8510 (Japan)

We observed the J=5−4 rotational lines of the normal species and three {sup 13}C isotopologues of HC{sub 3}N at the 45 GHz band toward two low-mass starless cores, L1521B and L134N (L183), using the Nobeyama 45 m radio telescope in order to study the main formation pathways of HC{sub 3}N in each core. The abundance ratios of the three {sup 13}C isotopologues in L1521B are derived to be [H{sup 13}CCCN]:[HC{sup 13}CCN]:[HCC{sup 13}CN] = 0.98 (±0.14):1.00:1.52 (±0.16) (1σ). The fractionation pattern is consistent with that at the cyanopolyyne peak in Taurus Molecular Cloud-1. This fractionation pattern suggests that the main formation pathway of HC{sub 3}N is the neutral–neutral reaction between C{sub 2}H{sub 2} and CN. On the other hand, their abundance ratios in L134N are found to be [H{sup 13}CCCN]:[HC{sup 13}CCN]:[HCC{sup 13}CN] = 1.5 (±0.2):1.0:2.1 (±0.4) (1σ), which are different from those in L1521B. From this fractionation pattern, we propose that the reaction between HNC and CCH is a possible main formation pathway of HC{sub 3}N in L134N. We find out that the main formation pathways of the same molecule are not common even in similar physical conditions. We discuss the possible factors that could make a difference in the fractionation pattern between L134N and L1521B/TMC-1.

• OSTI ID: 22875863
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 846; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CARBON 13
COSMIC GASES
CYANIDES
FRACTIONATION
MASS
MOLECULES
RADIO TELESCOPES