Carbon-chain molecule survey toward four low-mass molecular outflow
  sources
  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 (C$_2$H, C$_4$H, c--C$_3$H$_2$), HC$_{\rm 2n+1}$N (n=1,2), C$_{\rm
n}$S (n=2,3), and SO, HNC, N$_2$H$^+$. Hydrocarbons and HC$_3$N were detected
in all the sources, except for L1598, which had a marginal detection of C$_4$H
and a non-detection of HC$_3$N (J=2--1). HC$_5$N 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(HC$_3$N/N(N$_2$H$^+$)) 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, C$_4$H, c--C$_3$H$_2$, and
HC$_3$N with data from the PMO. We also find that HNC and NH$_3$ is
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.
