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Session 31 - The Diffuse Interstellar Medium, Progress and Puzzles - I.
Oral session, Tuesday, June 11
Historical Society,

[31.04] The Spatial Distribution and States of Warm and Cool HI

J. N. Bregman (University of Michigan)

The spatial distribution of the interstellar medium provides strong constraints on the underlying physics of the system. Observations of cool material reveal a wealth of information about the structure of HI, including the presence of sheets, clouds, shells, "worms", and other important structures. These observations lead to estimates of the filling factors of the various gaseous phases as well as useful limitations on existing models. There are several suggested models for the origin of many of the features seen in the ISM, some calculated using hydrodynamics codes, others with semi-analytic theory. The successes and failures of these models will be reviewed. The important contributors to pressure support of the gas, expected departures from pressure equilibrium, and the likely heating and cooling mechanisms for the gas will also be surveyed.

Program listing for Tuesday