The MSX galactic plane survey submillimeter results Original Research Article

The Midcourse Space Experiment (MSX) surveyed the Galactic plane within 5° latitude in four mid-infrared spectral bands. A set of full resolution (20″) 1.5°×1.5° images on 6″ pixel centers has been created in each spectral band by co-adding all the survey data. A lower (1.2′) resolution atlas of 10°×10° images provide large-scale panoramas of the plane. Both sets of images are valuable resources for identifying interesting objects for further study at other wavelengths. The low-resolution maps are ideally suited for comparison with molecular line surveys and one such comparison probes the star formation rate in the inner Galaxy. A new class of objects has been identified in the images, infrared dark clouds, which are silhouetted against the mid-infrared background emission from the interstellar medium in the Galactic plane. These clouds are dark out to 100 μm as evinced on the IRAS IRSA plates. Submillimeter emission traces the form of the dark cloud and reveals cores indicative of class 0 protostars.