THE MAGNETIC-FIELDS IN THE OPHIUCHUS AND TAURUS MOLECULAR CLOUDS

We discuss the significance of previously published OH Zeeman effect m easurements of the magnetic held in the rho Oph cloud (L1688) and also a new OH Zeeman effect measurement for the dark cloud core TMC-1C, th e latter obtained with the Arecibo telescope. Results for both of thes e clouds, like previously published OH Zeeman results for other dark c louds, show that the line-of-sight held strength /B-parallel to/ less than or equal to 10 mu G. The rho Oph cloud is significantly higher in column density than other clouds studied, and recent H I Zeeman effec t observations have revealed B-parallel to approximate to +10 mu G in the H I self-absorption region in front of the II derived from the OH Zeeman effect may indicate that OH poorly samples cloud. The low value s of B-parallel to derived from the OH Zeeman effect may indicate that OH poorly samples the dense gas in the rho Oph cloud, or else that th e cloud is in a state of supercritical collapse. The TMC-IC cloud core may have formed via ambipolar diffusion in a manner similar to recent modeling of dark cloud Barnard 1.