Millimeter and Optical Observations of Translucent Molecular Clouds

Abstract

Translucent molecular clouds with total visual extinctions A_ᴠᵗᵒᵗ ≈ 2−5 mag are of interest because they occupy the middle ground of parameter space between the classical diffuse molecular clouds, such as the ζ Oph cloud (A_ᴠᵗᵒᵗ ≈1 mag), and the dark clouds, such as TMC-1 (A_ᴠᵗᵒᵗ ≥ 10 mag). They have the advantage that they can be studied both by millimeter emission line techniques, as well as by optical absorption line observations, provided that there is a bright star located behind the cloud. The high-latitude molecular clouds fall into the same category.

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