Nitrogen sulfide in quiescent dark clouds

Abstract

We report the first detection of interstellar nitrogen sulfide (NS) in cold dark clouds. Several components of the 2Π1/2, J = 3/2 → 1/2 and J = 5/2 → 3/2 transitions were observed in TMC-1 and L134N. The inferred column density for TMC-1 is NNS ∼ 8 × 1012 cm-2 toward the NH3 peak in that cloud, and in L134N is NNS ∼ 3 × 1012 cm-2 toward the position of peak NH3 emission. These values correspond to fractional abundances relative to molecular hydrogen of fNS ∼ 8 × 10-10 for TMC-1, and fNS ∼ 6 × 10-10 for L134N. The NS emission is extended along the TMC-1 ridge and is also extended in L134N. The measured abundances are significantly higher than those predicted by some recent gas phase ion-molecule models.