The thesis goes on to extend the work of Bretherton (2003) and Moore et al. (2007) on the W3 Giant Molecular Cloud, by performing NH3 follow up of a sample of the cores discovered in the 850um SCUBA map and observing the whole cloud in 13CO(J=1-0) and C18O(J=1-0). - The NH3(1,1) and NH3(2,2) observations of the SCUBA cores used the fact that NH3 only traces the densest regions of the cloud, and hence can be used to find the temperature and kinematics of the cores themselves. This was used to test if the individual cores were virially bound, and from this find if cores in the more densely star-forming region of the cloud (High-Density Layer, HDL) were more likely to be bound than those in the Low-Density Layer (LDL). There are a mixture of virially bound and unbound cores in both the HDL and the LDL but no statistical difference in ratio of these between the two regions. This has an important bearing on models of environmentally-dependent star-formation, which divide into two categories; those, such as Collect and Collapse (Dale et al., 2007), which state that external pressures create dense structure, and those such as Radiatively- Driven Instability (RD I) (Bertoldi, 1989), which state that those external pressures cause dense structure to collapse. The evidence from this thesis favours models in which dense structure is created according to the Collect and Collapse scenario.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:571899 |
| Date | January 2012 |
| Creators | Allsopp, James |
| Publisher | Liverpool John Moores University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
Page generated in 0.0042 seconds