TWO MASSIVE, LOW-LUMINOSITY CORES TOWARD INFRARED DARK CLOUDS

This article presents high-resolution interferometric mosaics in the 850 mu m wave band of two massive, quiescent infrared dark clouds. The two clouds were chosen based on their likelihood to represent environments preceding the formation of massive stars. The brightest compact sources detected in each cloud have masses approximate to 110 M-circle dot and approximate to 60 M-circle dot with radii <0.1 pc, implying mean densities of < n > approximate to 106 cm(-3) and < N > approximate to 1 g cm(-2). Supplementary data show these cores to be cold and inactive. Low upper limits to their bolometric luminosities and temperatures place them at a very early stage of evolution, while current models of massive star formation suggest they have the potential to form massive stars.