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Studies of the 21-cm line in dense dust clouds

University of British Columbia

Using the 26 m paraboloid at the Dominion Radio Astrophysical Observatory, sufficient 21-cm line data have been obtained on thirteen dense dust clouds to give a measure of the significance of an excess or a deficit in the hydrogen emission from these objects, as compared with nearby surrounding regions of the sky. The analysis of these data indicates that four of these clouds show significant decreases in the hydrogen emission. If the widths of these deficits are to be interpreted as thermal broadening within a single cloud, kinetic temperatures obtained are far in excess of those indicated by normal OH emission from these same objects. If the OH and H are in thermodynamic equilibrium and the chemical abundances are normal, it is thought that the deficits are due to the hydrogen being in molecular form. However, measurements of higher spatial and velocity resolution are needed to rule out the possibility of a cold absorbing cloud.

Text

2011-04-29

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http://hdl.handle.net/2429/34167

Physics

University of British Columbia

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