TY - JOUR
T1 - Long Carbon Chains in the Warm Carbon-chain-chemistry Source L1527
T2 - First Detection of C7H in Molecular Clouds
AU - Araki, Mitsunori
AU - Takano, Shuro
AU - Sakai, Nami
AU - Yamamoto, Satoshi
AU - Oyama, Takahiro
AU - Kuze, Nobuhiko
AU - Tsukiyama, Koichi
N1 - Funding Information:
We thank the staff at the National Radio Astronomy Observatory for help with the observations. We are grateful to the anonymous reviewer for valuable comments. We thank Dr. David Frayer for his help in the observations with the GBT. MA thanks Grant-in-Aid for Scientific Research on Innovative Areas (grant No. 25108002), Grant-in-Aid for Scientific Research (C) (grant No. 15K05395), and the support from the grant from Institute for Quantum Chemical Exploration.
Funding Information:
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under a cooperative agreement by Associated Universities, Inc.
Publisher Copyright:
© 2017. The American Astronomical Society. All rights reserved..
PY - 2017/9/20
Y1 - 2017/9/20
N2 - Long carbon-chain molecules were searched for toward the low-mass star-forming region L1527, which is a prototypical source of warm carbon-chain chemistry (WCCC), using the 100 m Green Bank Telescope. Long carbon-chain molecules, C7H (2Π1/2), C6H (2Π3/2 and 2Π1/2), CH3C4H, and C6H2 (cumulene carbene, CCCCCCH2), and cyclic species of C3H and C3H2O were detected. In particular, C7H was detected for the first time in molecular clouds. The column density of C7H is determined to be 6 × 1010 cm-2. The column densities of the carbon-chain molecules including CH3C4H and C6H in L1527 relative to those in the starless dark cloud Taurus Molecular Cloud-1 Cyanopolyyne Peak (TMC-1 CP) tend to be systematically lower for long carbon-chain lengths. However, the column densities of C7H and C6H2 do not follow this trend and are found to be relatively abundant in L1527. This result implies that these long carbon-chain molecules are remnants of the cold starless phase. The results - that both the remnants and WCCC products are observed toward L1527 - are consistent with the suggestion that the protostar can also be born in the parent core at a relatively early stage in the chemical evolution.
AB - Long carbon-chain molecules were searched for toward the low-mass star-forming region L1527, which is a prototypical source of warm carbon-chain chemistry (WCCC), using the 100 m Green Bank Telescope. Long carbon-chain molecules, C7H (2Π1/2), C6H (2Π3/2 and 2Π1/2), CH3C4H, and C6H2 (cumulene carbene, CCCCCCH2), and cyclic species of C3H and C3H2O were detected. In particular, C7H was detected for the first time in molecular clouds. The column density of C7H is determined to be 6 × 1010 cm-2. The column densities of the carbon-chain molecules including CH3C4H and C6H in L1527 relative to those in the starless dark cloud Taurus Molecular Cloud-1 Cyanopolyyne Peak (TMC-1 CP) tend to be systematically lower for long carbon-chain lengths. However, the column densities of C7H and C6H2 do not follow this trend and are found to be relatively abundant in L1527. This result implies that these long carbon-chain molecules are remnants of the cold starless phase. The results - that both the remnants and WCCC products are observed toward L1527 - are consistent with the suggestion that the protostar can also be born in the parent core at a relatively early stage in the chemical evolution.
KW - ISM: clouds
KW - ISM: individual objects (L1527)
KW - ISM: molecules
KW - astrochemistry
KW - radio lines: ISM
UR - http://www.scopus.com/inward/record.url?scp=85030164689&partnerID=8YFLogxK
U2 - 10.3847/1538-4357/aa8637
DO - 10.3847/1538-4357/aa8637
M3 - Article
AN - SCOPUS:85030164689
VL - 847
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 1
M1 - 51
ER -