CO observations of NGC 1579 (S222) and S239

The 2.6 mm lines of 12CO and 13CO have been observed toward the small galactic diffuse nebulae NGC 1579 (S222) and S239. The H92α recombination line has also been detected from NGC 1579. Toward NGC 1579, we have observed evidence for self-absorption in the 12CO line. For both regions, high-velocity wings and line broadening are observable in the 12CO line; the features observed toward S239 suggest ordered, free-fall collapse of a localized region of the cloud onto a newborn stellar cluster. Examination of the available data suggests that NGC 1579 is both a reflection nebula (illuminated by LkHα 101), and an obscured H ii region excited by a star of spectral type near B1, while S239 is a reflection nebula or a Herbig-Haro object. Our studies of these regions show that line widening in CO is at least as important an indicator of star-formation activity as enhanced line emission