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| EPoS Contribution |
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The Early Phase of Molecular Cloud Formation
Kevin A. Douglas School of Physics, University of Exeter, Exeter, UK | |
| Molecular clouds traced by CO observations are already in an advanced evolutionary stage, in which a star formation nidus may already be established. The difficulty in detecting cold molecular hydrogen directly implies that the onset of molecular cloud formation is not well observed or understood. The use of HI self-absorption as a probe of regions containing cold, dense hydrogen, much of which is likely molecular, may be regarded as a powerful observational diagnostic of the earliest phase of molecular cloud formation. In recent simulations we have shown that molecular hydrogen forms from atomic HI clouds as the HI gas undergoes shock cooling and compression at the interface of a Galactic spiral arm. Moreover, synthetic HI datacubes of this simulation show that HI self-absorption features are produced at these shock sites. | |
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| Caption: Radial velocity of HI gas against distance from the observer, for a Synthetic HI Galactic observation of an SPH spiral galaxy. HI self-absorption is predicted, and observed, between -40 and -50 km/s. | |
| Collaborators: D.A. Acreman, Exeter, UK C.L. Dobbs, Exeter, UK C.M. Brunt, Exeter, UK |
Suggested Session:
Molecular Clouds |