Program: GS-2004A-Q-7

Hot molecular cores (HMCs) represent the earliest observable stages of massive star formation. These sources are heavily embedded and young, and can only be observed between wavelengths of 3 microns and a few mm. Newly developed models of these HMC phases of massive star formation enable one to determine for the first time detailed physical properties of these sources, such as accretion rate and central star luminosity, from multiple wavelength observations in the mid-infrared. In May of 2001, a HMC was detected for the first time at mid-infrared wavelengths at Gemini North using OSCIR. Recently, three more HMCs have been discovered in the mid-infrared. These four sources are the only known mid-infrared bright HMCs. I propose to perform multiple wavelength mid-infrared photometry on these HMCs, and through the use of the models, determine for the first time the physical properties of the earliest observable stages of massive stars. (This is a revised and resubmitted version of a proposal that was awarded time in 2002A, again in 2002B, and DD time in 2003B but was not completed due to the T?ReCS delivery delays and weather.)