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Session 31 - The Diffuse Interstellar Medium, Progress and Puzzles - I.
Oral session, Tuesday, June 11
Historical Society,
An AAS meeting in Madison provides an excellent opportunity for this special session on the Diffuse Interstellar Medium. It is a topic on which many here have worked long and hard, tending to believe that until its intricacies are sufficienty grasped, one will likely misinterpret much of the behavior of the post-recombination Universe. In addition, the larger community of those who work in this arena, both in the US and elsewhere, is active, stimulating, and decidedly challenging. It is a distinct pleasure to host a general review of their progress, and the disturbing puzzles that remain. There have been a variety of conceptions of the interstellar medium; each a partially successful synthesis of an enormous amount of observational data. They include ideas about how the gas is distributed, and why; about where it is ionized, and why; about where very hot gas is located and with what prevalence, and why; about the roles of cosmic rays and magnetic fields in the overall structure and activity of the system, and occasionally even some sense of how things might be different at other galactic radii, or how the whole structure responds to disturbance by spiral density waves. This special session focuses primarily on the observational material, but with specific attention to how the data limit the range of acceptable pictures. It is also intended to highlight key puzzles, describe anticipated progress from new instrumentation, and provide a spirited attempt to imagine how things might actually be out there--and why.
