Nitrogen sulfide in quiescent dark clouds

We report the first detection of interstellar nitrogen sulfide (NS) in cold dark clouds. Several components of the (2)Pi(sub 1/2), J = 3/2 to 1/2 and J = 5/2 to 3/2 transitions were observed in TMC-1 and L134N. The inferred column density for TMC-1 is N(sub NS) approximately 8 x 10(exp 12)/sq cm toward the NH3 peak in that cloud, and in L134N is N(sub NS) approximately 3 x 10(exp 12)/sq cm toward the position of peak NH3 emission. These values correspond to fractional abundances relative to molecular hydrogen of f(sub NS) approximately 8 x 10(exp -10) for TMC-1, and f(sub NS) approximately 6 x 10(exp -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.