CO observations of the bright-rimmed cloud B 35.

Abstract

Detailed observations of millimeter-wave emission from $sup 12$CO and $sup 13$CO are made throughout the bright-rimmed molecular cloud B35 and compared with optical photographs. A ridge of enhanced $sup 12$CO brightness temperature is observed directly behind and along the bright-rimmed ionization front which forms the western border of the molecular cloud. Measurements of CO column density through the cloud across both the ridge and the ionization front show that the column density peaks near the ridge and, like the CO brightness temperature, steeply decreases across the ionization front. It is shown that modification of the cloud conditions by shock waves can explain observations and account for the observed CO cooling rates in the cloud. Cloud heating by embedded young stars is also possible, and infrared observations are suggested as a means of distinguishing between the two heating models. (AIP)