Mid‐Infrared Imaging of Star‐forming Regions Containing Methanol Masers

We present a mid-infrared imaging survey of 21 sites of massive star formation associated with methanol masers. Images were obtained from the Cerro Tololo Inter-American Observatory 4 m Blanco telescope using the University of Florida imager/spectrometer OSCIR. Of the 10 sites where the methanol masers are distributed in a linear fashion, we find three sources that are elongated at the same position angle as their linear methanol maser distributions. It is believed that these elongated mid-infrared objects are indeed circumstellar disks. It was found that the masers may arise inside the mid-infrared emitting regions of these young stellar objects, indicating that the methanol masers may be pumped by mid-infrared photons. Many mid-infrared sources in our survey have no detectable radio continuum emission, and we advance the hypothesis that these sources are lower mass, nonionizing stars.