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Session 10 - Interstellar Medium and Star Formation.
Display session, Monday, June 08
Atlas Ballroom,
We have used the SHARC bolometer camera at the Caltech Submillimeter Observatory to map the distribution of the broad-band 350 micron continuum emission toward the Orion A Molecular Cloud. A comparison of the 350 and 1100 micron flux densities in OMC-1 indicates a strong variation of the grain emissivity exponent along the Orion Ridge. The lowest value (beta= 1.75) is found toward the Orion Bar, while the highest value is found north of IRc2. This variation is consistent with the destruction of grain mantles by the UV photons from the Trapezium cluster. The 350 micron continuum emission in the Orion Bar correlates well with the CO J=6-5 peak brightness temperature and is shifted from the molecular bar traced by 13CO J=6-5 emission. This indicates that the dust emission originates in the outer PDR layers with increased kinetic temperature. Over 30 compact dust sources have been detected in OMC-2 and OMC-3. The dust temperature is around 18K for most of the compact sources, but for three sources it may be only around 10K or is very optically thick.
