2018MNRAS.480.3503S

We detected OH 18 cm main line emission from 5 of 7 positions in the intermediate-velocity molecular cloud (IVMC) G211+63. These are the first detections of hydroxyl in IVMCs. Our OH detections at A_V levels ranging from 0.24 to 0.27 mag reinforce the notion that these lines can efficiently trace diffuse, low-extinction molecular gas. N(OH) is derived for a range of excitation temperatures (5-30 K) and likely falls between 1 and 16 x 10¹³ cm^–2. The corresponding N(H₂) values are consistent both with estimates derived from E(B - V) and CO data. Estimates of the cloud mass from the OH data range from 26 to 820 M_☉ for distances from 100 to 400 pc and T_ex from 5 to 10 K. These values are 3-20 times less than the virial mass of the cloud. It is likely IVMCs resemble high-latitude clouds in this respect. If so, they are transient structures breaking up on time-scales of ∼10⁶ yr^.