| 1. |
- Wilson, C. D., et al.
(författare)
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Submillimeter emission from water in the W3 region
- 2003
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 402, s. L59-L62
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Tidskriftsartikel (refereegranskat)abstract
- Using the Odin satellite, we have mapped the submillimeter emission from the 110-101 transition of ortho-water in the W3 star-forming region. A 5arcminx 5arcmin map of the W3 IRS4 and W3 IRS5 region reveals strong water lines at half the positions in the map. The relative strength of the Odin lines compared to previous observations by SWAS suggests that we are seeing water emission from an extended region. Across much of the map the lines are double-peaked, with an absorption feature at -39 km s-1; however, some positions in the map show a single strong line at -43 km s-1. We interpret the double-peaked lines as arising from optically thick, self-absorbed water emission near the W3 IRS5, while the narrower blue-shifted lines originate in emission near W3 IRS4. In this model, the unusual appearance of the spectral lines across the map results from a coincidental agreement in velocity between the emission near W3 IRS4 and the blue peak of the more complex lines near W3 IRS5. The strength of the water lines near W3 IRS4 suggests we may be seeing water emission enhanced in a photon-dominated region. Based on observations with Odin, a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes), and Centre National d'Études Spatiales (CNES). The Swedish Space Corporation was the industrial prime contractor and is also responsible for the satellite operation.
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| 2. |
- Gahm, G. F., et al.
(författare)
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The Threaded Molecular Clumps of Chamaeleon III
- 2002
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 389:2, s. 577-588
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Tidskriftsartikel (refereegranskat)abstract
- We have mapped large areas in the complex of molecular clouds with the SEST in 13CO( J=1-0) and in C 18O( J=1-0). The stronger CO emission coincides with areas of cold dust emission, which is distributed in long, but thin, wavy filaments. We identify some 40 clumps of enhanced CO emission in these filaments. In the southern part of the clumps are equidistant along the main zig-zag shaped filament. Here we find two systems of filaments moving at different radial velocities. At least part of the zig-zag patterns visible on optical images may be caused by overlapping filaments. All clumps are small (typically 0.02-0.05 pc in radius), and of small mass (typically 0.1-0.7 , when assuming the "standard" C 18O/H 2 column density ratio). Also the average number densities are small, cm -3, and the density contrast between clump and interclump gas is only ~10. In addition the values of are unusually small, 0.03-0.33. These clumps have smaller masses than those so far identified in other molecular clouds. Previously reported clumps of larger masses in turn out to be composed of assemblies of clumps. There are no signs of star formation in (unlike and ), and our results indicate also that such activity is not expected. However, with the velocity dispersion of 0.2 km s -1 the clumps would leave the thin filaments on short timescales, and if the clumps as such are not confined by some external force, they would also lose their identity on even shorter timescales. We discuss the possibility that the clumps are confined by electromagnetic forces, and show that this may work with reasonable assumptions on the required magnetic field strength. We also discuss the possibility that the clumps are attached to magnetic ropes along the filamentary axis, in which case the clumps could swing back and forth perpendicularly to the axis, like they were threaded on elastic strings.
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