Doug Johnstone et al. 2006 ApJ 639 259 doi:10.1086/499258
Doug Johnstone1,2, Henry Matthews3 and George F. Mitchell4
Show affiliationsWe present results from a survey of a 1300 arcmin2 region of the Orion B South molecular cloud, including NGC 2024, NGC 2023, and the Horsehead Nebula (B33), obtained using the Submillimetre Common-User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope (JCMT). Submillimeter continuum observations at 450 and 850 μm are discussed. Using an automated algorithm, 57 discrete emission features ("clumps") are identified in the 850 μm map. The physical conditions within these clumps are investigated under the assumption that the objects are in quasi-hydrostatic equilibrium. The best-fit dust temperature for the clumps is found to be Td = 18 ± 4 K, with the exception of those associated with the few known far-infrared sources residing in NGC 2024. The latter internally heated sources are found to be much warmer. In the region surrounding NGC 2023, the clump dust temperatures agree with clump gas temperatures determined from molecular line excitation measurements of the CO molecule. The bounding pressure on the clumps lies in the range log(k-1P cm3 K-1) = 6.1 ± 0.3. The cumulative mass distribution is steep at the high-mass end, as is the stellar initial mass function. The distribution flattens significantly at lower masses, with a turnover around 3-10 M
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infrared: ISM; ISM: clouds; ISM: individual (B33, NGC 2023, NGC 2024, Orion B South); ISM: structure; stars: formation
Issue 1 (2006 March 1)
Received 2005 March 17, accepted for publication 2005 October 21
Doug Johnstone et al. 2006 ApJ 639 259
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