Assigned ID: 384 ----- Submission 1 (Fri Jan 21 21:14:54 GMT 2005) ----- This theory proposal requests support to develop a combination of chemistry and hydrodynamics, and apply it to the analysis and interpretation of HST observations of knots in the Helix. They offer a laboratory to understand flows from molecular condensations into a low-density ionized medium, and so have implications for other environments, such as H II regions and Starbursts. The project involves developing the chemistry and dynamics in the spectral simulation code Cloudy. Cloudy is widely used across the astronomical community, so the proposed developments will have broad application. Recent NICMOS observations detail aspects of the flow from the molecular core, where the gas is surprisingly warm, into the ionized region, where STIS and WFPC2 measure the surface brightness and relative intensities of emission lines. We will make the following improvements: The heavy element chemical network (including CO) and a complete model of molecular hydrogen will be integrated into our treatment of dynamics. Our previous work had only included atomic and ionized regions. We will consider strongly divergent flows, as seen in the Helix; our previous work used only a plane-parallel geometry. We will use the improved code to create evolutionary grids that follow changes as the system ages. Our goals are to determine the mass, mass-loss rate, and lifetime of the knots, and identify the mechanisms responsible for their current physical state.

ISM AND CIRCUMSTELLAR MATTER 12 67443 salary and travel split over two years false 0.0 false false false true false SUPPORTED