2021A&A...648L...3C

We report the detection of the sulfur-bearing species NCS, HCCS, H₂CCS, H₂CCCS, and C₄S for the first time in space. These molecules were found towards TMC-1 through the observation of several lines for each species. We also report the detection of C₅S for the first time in a cold cloud through the observation of five lines in the 31-50GHz range. The derived column densities are N(NCS)=(7.8±0.6)x10¹¹cm^–2, N(HCCS)=(6.8±0.6)x10¹¹cm^–2, N(H₂CCS)=(7.8±0.8)x10¹¹cm^–2, N(H₂CCCS)=(3.7±0.4)x10¹¹cm^–2, N(C₄S)=(3.8±0.4)x10¹⁰cm^–2, and N(C₅S)=(5.0±1.0)x10¹⁰cm^–2. The observed abundance ratio between C₃S and C₄S is 340, that is to say a factor of approximately one hundred larger than the corresponding value for CCS and C₃S. The observational results are compared with a state-of-the-art chemical model, which is only partially successful in reproducing the observed abundances. These detections underline the need to improve chemical networks dealing with S-bearing species.