The galactic distribution of molecules (A CO survey)

Abstract

The J = 1 → 0 emission of CO has been surveyed in the galactic plane between ℓ = -10° and +90° with a 1′ beam sampling every degree. Molecular clouds emitting in the CO line are plentiful over the inner region of the galaxy. Their greatest number occurs in the galactic nucleus and at a radius of 5.5 kpc — a distribution similar to radio H II regions but very different from that previously derived for atomic hydrogen. The total mass in molecular clouds is found to be 1 → 3 10^9 M_⊙, and each typically has 10^5 M_⊙, an average density of 500 cm^(−3), and a temperature of 7°K. These results suggest that most of the interstellar medium in the interior of the galaxy is molecular H_2.

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