Abstract
We report the detection of the sulfur-bearing species NCS, HCCS, H(2)CCS, H(2)CCCS, and C(4)S 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 C(5)S for the first time in a cold cloud through the observation of five lines in the 31-50 GHz range. The derived column densities are N(NCS) = (7.8±0.6)×10(11) cm(-2), N(HCCS) = (6.8±0.6)×10(11) cm(-2), N(H(2)CCS) = (7.8±0.8)×10(11) cm(-2), N(H(2)CCCS) = (3.7±0.4)×10(11) cm(-2), N(C(4)S) = (3.8±0.4)×10(10) cm(-2), and N(C(5)S) = (5.0±1.0)×10(10) cm(-2). The observed abundance ratio between C(3)S and C(4)S is 340, that is to say a factor of approximately one hundred larger than the corresponding value for CCS and C(3)S. 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.