Microwave spectroscopy and gravitational collapse
Thesis/Dissertation
·
OSTI ID:6683595
The author reports on high-resolution observations of NH/sub 3/ in the molecular-cloud cores surrounding five ultracompact H II regions, G10.6-0.4, W33-main, NGC7538-IRS1, W3(OH), and G34.3 + 0.2. Three of the sources, G10.6-0.4, W3((OH), and G34.3 + 0.2 show velocity structure consistent with gravitational collapse of the core onto the central H II region. G10.6-0.4, which has been most extensively observed, shows a hot centrally condensed core with temperature scaling as r/sup 1/2/ and density as approximately r/sup -2/. The temperature and density maps show strong velocity gradients consistent with rotational and infall motions. At a spatial resolution of better than 0.014 pc, the accretion flow onto the H II region is resolved and can be characterized by differential rotation and accelerating collapse. The projected angular velocity was determined at four different radii from the central source. The other two sources in the survey, W33-main and NGC7538-IRS1, show evidence that the molecular gas surrounding the H II regions is driven by strong outflow from the central stars.
- Research Organization:
- Harvard Univ., Cambridge, MA (USA)
- OSTI ID:
- 6683595
- Country of Publication:
- United States
- Language:
- English
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