Shocked and Scorched: A GREAT Investigation of [CII] and [OI] emission fromfree-floating Evaporating Gas Globules in Massive Star Formation Regions

We present first results from a GREAT program to study the atomic component of select members of a new class of tadpole-shaped free-floating evaporating gas globules (frEGGs) in massive star-formation regions. Since discovering the most prominent member of this class in an HST imaging survey, we have now identified substantial populations of such objects in several massive star-forming regions using Spitzer IRAC 8 micron images. By virtue of their distinct, isolated morphologies, frEGGs are ideal astrophysical laboratories for probing star formation in irradiated environments. Our molecular-line observations (e.g., CO, 13CO J=2-1 & HCO+ J=3-2) reveal the presence of dense molecular cores associated with these objects, with total masses of cool (∼50 K) molecular gas exceeding 0.5-5 Msun, and our radio continuum imaging of a few reveals bright photo-ionized peripheries in these objects. Our GREAT study of 3 frEGGs has allowed us to detect the warm (few x 100 K) atomic gas that is expected to exist in a photon-dominated region surrounding the molecular gas and determine its mass, and probe the photoevaporative flow that is expected to drive the evolution of these objects. Our SOFIA data (together with existing multiwavelength data), when compared with results from sophisticated 3-D numerical simulations, will provide a unique window into the dynamical and chemical evolution of these irradiated dense gaseous globules, and the star-formation process within them.