Molecular Clouds in the Outer Milky Way Galaxy

Abstract

This is to follow up the report by Kutner and Mead (1981) of extensive CO emission from molecular clouds between R = 10 and 16 kpc. In the initial report, three strips were mapped, at b = 1.3°, 1.5°, and 1.7°, with 1 ranging from 55° to 95°, in steps of 0.1°. Maps of five giant molecular clouds (GMCs) were also presented. It was argued that CO emission from outer galaxy clouds is weaker than that from inner galaxy clouds partly because of a lower kinetic temperature in the outer galaxy clouds, and that this had to be taken into account in mass estimates of molecular material in the galaxy. It was estimated that the mass of H₂ in the outer galaxy is ~ 1/3 that in the inner galaxy.