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| Paper: |
The Southern Coalsack |
| Monograph: |
5, Handbook of Star Forming Regions:
Volume II, The Southern Sky |
| Page: |
222 |
| Authors: |
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| Abstract: |
The Southern Coalsack is the most prominent, isolated dark cloud in the southern Milky Way. It is situated on the Galactic equator at l = 303° and has a diameter of about 6°. The visual extinction over the cloud varies by between 1 and 3 magnitudes but can be much higher in small condensations and globules. From photometric studies the distance to the Coalsack has been estimated to ∼ 150 pc. A CO (1–0) survey of the whole cloud showed that it is very fragmented, consisting of clumps and filaments, and the total mass is estimated to ∼ 3500M⊙. A cloud of this size and mass would be expected to contain young stars, but so far none has been found, although searches have been made for T Tauri stars, flare stars, HH objects, and IRAS point sources with color-color characteristics of young stars. The Coalsack may not be forming stars because it contains an unusually small amount of dense gas compared to typical star-forming clouds, as indicated by a 13CO survey, or it is a young molecular cloud complex, implied by the fact that the densest globule is not centrally condensed, which is normally the case for globules and star-forming cores. |
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