On the redistribution of OB star luminosity and the warming of nearby molecular clouds

Abstract

IRAS observations of the neighborhoods of six H II regions in the outer Galaxy have been correlated with CO maps of the same regions. It is found that more than half of the far-infrared luminosity from within ≡25 - 75 pc of the ionizing stars is contributed by dust associated with molecular clouds; however, a major and temporally increasing fraction of the OB cluster starlight is not absorbed locally. The radiated energy of open OB star clusters is found to be distributed in the interstellar medium in accordance with the solid angle subtended by molecular clouds at the cluster. This solid angle tends to decrease with increasing cluster age, as the clouds recede from the clusters. A model is proposed to describe the interstellar environment of OB star clusters as a function of time.