Observations of CO/J = 2-1/ emission from molecular clouds

Abstract

Spectra and strip maps of CO(J = 2-1) emission are presented for a variety of molecular clouds within the Galaxy. In most cases data are also presented for the less-abundant species (C-13)O and C(O-18), and, where possible, comparison is made between the CO(2-1) data and equivalent CO(1-0) spectra and maps. A discussion is given of the behavior of line widths and spatial extents as a function of CO line opacity. From the line widths it is deduced that for some dense molecular clouds the CO(1-0) optical depth is in the range 20-100.