C4H and c-C3H2, as unsaturated hydrocarbon molecules, are important for forming large organic molecules in the interstellar medium. We present mapping observations of C4H (N=9−8) lines, c-C3H2 (JKa,Kb=21,2-10,1) %at 85338.894 MHz and H13CO+ (J=1−0) %at 86754.2884 MHz toward 19 nearby cold molecular cores in the Milky Way with the IRAM 30m telescope. C4H 9--8 was detected in 13 sources, while c-C3H2 was detected in 18 sources. The widely existing C4H and c-C3H2 molecules in cold cores provide material to form large organic molecules. Different spatial distributions between C4H 9--8 and c-C3H2 2--1 were found. The relative abundances of these three molecules were obtained under the assumption of local thermodynamic equilibrium conditions with a fixed excitation temperature. The abundance ratio of C4H to c-C3H2 ranged from 0.34 ± 0.09 in G032.93+02 to 4.65 ± 0.50 in G008.67+22. A weak correlation between C4H/H13CO+ and c-C3H2/H13CO+ abundance ratios was found, with a correlation coefficient of 0.46, which indicates that there is no tight astrochemical connection between C4H and c-C3H2 molecules.
@article{arxiv.2406.19740,
title = {Spatial distribution of C4H and c-C3H2 in cold molecular cores},
author = {Yijia Liu and Junzhi Wang and Shu Liu and Ningyu Tang and Yan Gong and Yuqiang Li and Juan LI and Rui Luo and Yani Xu},
journal= {arXiv preprint arXiv:2406.19740},
year = {2024}
}