A Search for Mid-Infrared Emission from Hot Molecular Core Candidates

We present here mid-infrared images of seven sites of water maser emission thought to be associated with the hot molecular core (HMC) phase of massive star formation. We have detected mid-infrared emission from the locations of two of these HMC candidates, G11.94-0.62 and G45.07+0.13. From our observations we derived lower limit estimates of the luminosities for the exciting sources in these two HMC candidates. We find that the estimates are consistent with the hypothesis that the HMCs are internally heated by massive B- and O-type stars. We observed two sites with HMCs previously claimed to be detected in the mid-infrared, G19.61-0.23 and G34.26+0.15; however, we did not detect mid-infrared emission from either HMC location. We place new upper limits on the mid-infrared flux densities for these HMCs that are much lower than their previously reported flux densities. We were also able to obtain extremely accurate astrometry for our mid-infrared observations of G9.62+0.19 and conclude that the mid-infrared emission previously thought to be coming from the HMC in this field is in fact coming from a different source altogether.