10(51) ERGS - THE EVOLUTION OF SHELL SUPERNOVA-REMNANTS

This paper reports on the workshop ''10(51) Ergs: The Evolution of She ll Supernova Remnants,'' hosted by the University of Minnesota, 1997 M arch 23-26. The workshop was designed to address fundamental dynamical issues associated with the evolution of shell supernova remnants and to understand better the relationships between supernova remnants and their environments. Although the title points only to classical, shell SNR structures, the workshop also considered dynamical issues involvi ng X-ray-filled composite remnants and pulsar-driven shells, such as t hat in the Crab Nebula. Approximately 75 observers, theorists, and num erical simulators with wide-ranging interests attended the workshop. A n even larger community helped through extensive on-line debates prior to the meeting to focus issues and galvanize discussion. In order to deflect thinking away from traditional patterns, the workshop was orga nized around chronological sessions for ''very young,'' ''young,'' ''m ature,'' and ''old'' remnants, with the implicit recognition that thes e labels are often difficult to apply. Special sessions were devoted t o related issues in plerions and ''thermal X-ray composites.'' Controv ersy and debate were encouraged. Each session also addressed some unde rlying, general physical themes: How are supernova remnant (SNR) dynam ics and structures modified by the character of the circumstellar medi um (CSM) and the interstellar medium (ISM), and vice versa? How are ma gnetic fields generated in SNRs and how do magnetic fields influence S NRs? Where and how are cosmic rays (electrons and ions) produced in SN Rs, and how does their presence influence or reveal SNR dynamics? How does SNR blast energy partition into various components over time, and what controls conversion between components? In lieu of a proceedings volume, we present here a synopsis of the workshop in the form of bri ef summaries of the workshop sessions. The sharpest impressions from t he workshop were the crucial and underappreciated roles that environme nts have on SNR appearance and dynamics and the critical need for broa d-based studies to understand these beautiful but enigmatic objects.