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We present high-resolution, multiwavelength continuum and molecular-lineimages of the massive star forming region IRAS 18317-0757. The IR through mmspectral energy distribution can be approximated by a two-temperature model (25and 63 K) with a total luminosity of approximately log(L/Lsun)=5.2. Previoussubmm imaging resolved this region into a cluster of 5 dust cores, one of whichis associated with the UCHII region G23.96+0.15, and another with an H2O maser.In our new 2.7 mm continuum image, only the UCHII region is detected, withtotal flux and morphology in good agreement with the free-free emission in VLAcm-wave maps. For the other four objects, the nondetections at 2.7 mm and inthe MSX mid-IR bands are consistent with cool dust emission with a temperatureof 13-40K and luminosity of 1000-40000 Lsun. By combining single-dish andinterferometric data, we have identified over two dozen virialized C18O coresin this region that contain ~40% of the total molecular gas mass present. Whilethe overall extent of the C18O and dust emission is similar, the emission peaksdo not correlate well in detail. At least 11 of the 123 stars identified by2MASS in this region are likely to be within the star-forming cluster. Twostars (both associated with the UCHII region) were previously identified as Ostars via IR spectroscopy. Most of the rest of the reddened stars have noobvious correlation with the C18O cores or the dust cores. In summary, ourobservations indicate that considerable fragmentation of the molecular cloudhas taken place during the time required for the UCHII region to form and the Ostars to become detectable at IR wavelengths. Additional star formation appearsto be ongoing on the periphery of the central region, where up to four B-type(proto)stars have formed among a substantial number of C18O molecular cores.

IRAS 18317-0757: A Cluster of Embedded Massive Stars and Protostars