Carbon-chain molecule survey toward four low-mass molecular outflow sources

¹ Department of Astronomy, Yunnan University, Key Laboratory of Astroparticle Physics of Yunnan Province, Kunming 650091, PR China
e-mail: chaozhangchz@163.com
² Department of Astronomy, School of Physics, Peking University, Beijing 100871, PR China
e-mail: ywu@pku.edu.cn
³ Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, PR China
⁴ CAS Key Laboratory of FAST, National Astronomical Observatories, CAS, Beijing 100012, PR China
⁵ NAOC-UKZN Computational Astrophysics Centre (NUCAC), University of KwaZulu-Natal, Durban 4000, South Africa
⁶ Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi 830011, PR China
⁷ Key Laboratory of Radio Astronomy, Chinese Academy of Sciences, Urumqi 830011, PR China

Received: 5 August 2020
Accepted: 5 March 2021

Abstract

We performed a carbon-chain molecule (CCM) survey toward four low-mass outflow sources, IRAS 04181+2655 (I04181), HH211, L1524, and L1598, using the 13.7 m telescope at the Purple Mountain Observatory (PMO) and the 65 m Tian Ma Radio telescope at the Shanghai Observatory. We observed the following hydrocarbons (C₂H, C₄H, c–C₃H₂), HC_2n+1N (n = 1, 2), C_nS (n = 2, 3), and SO, HNC, N₂H⁺. Hydrocarbons and HC₃N were detected in all the sources, except for L1598, which had a marginal detection of C₄H and a non-detection of HC₃N (J = 2–1). HC₅N and CCCS were only detected in I04181 and L1524, whereas SO was only detected in HH211. L1598 exhibits the lowest detection rate of CCMs and is generally regarded to be lacking in CCMs source. The ratio of N(HC₃N/N(N₂H⁺)) increases with evolution in low-mass star-forming cores. I04181 and L1524 are carbon-chain-rich star-forming cores that may possibly be characterized by warm carbon-chain chemistry. In I04181 and L1524, the abundant CCCS can be explained by shocked carbon-chain chemistry. In HH211, the abundant SO suggests that SO is formed by sublimated S⁺. In this study, we also mapped HNC, C₄H, c–C₃H₂, and HC₃N with data from the PMO. We also find that HNC and NH₃ are concentrated in L1524S and L1524N, respectively. Furthermore, we discuss the chemical differences between I04181SE and I04181W. The co-evolution between linear hydrocarbon and cyanopolyynes can be seen in I04181SE.