Diffuse molecular clouds at high galactic latitude

Abstract

The IRAS 60 and 100 μm flux from cirrus clouds are commonly explained by dust continuum emission. But this explanation in some cases requires unexpectedly high dust temperatures.We argue that the contribution of fine structure emission of neutral oxygen, O°(63 μm), can be significant in the IRAS 60 μm band. The 0°(63 μm) line emission together with the dust continuum emission offers a plausible explanation of the observed flux ratio I(60)/I(100), as well as of its variation across individual clouds. We also discuss the clumpy/filamentary structure of these clouds.