Intermediate-velocity molecular gas at high northern Galactic latitudes

Abstract

We surveyed the CO(1-0) transition in 16 regions at Galactic latitudes > 45° which contain compact dust cores less than half a degree in size with E(B - V) values ∼ 0.1 mag. We discovered three new intermediatevelocity molecular clouds and two high-latitude molecular clouds with more typical local standard of rest velocity (∼0 km s-1). The three intermediate-velocity molecular clouds (detected in CO emission in 11 lines of sight) nearly double the number of previously known, CO-emitting clouds. In order to detect the CO(1-0) line, N(H2) values of at least 1019 cm∼2 are necessary, implying that the molecular/atomic fraction of these objects is significant and is in contrast to the primarily atomic lines of sight with log N(H2) < 17.3 detected in absorption by FUSE. The three molecular clouds are projected on and likely associated with a previously known intermediate-velocity Hi feature known as the Intermediate Velocity Spur that may extend to the Galactic halo. © 2010. The American Astronomical Society. All rights reserved. Printed in the U.S.A.