Director of Graduate Studies for Astronomy, University of Minnesota, 2006-2019.
UMN Senate: 2005-present.
UMN I.T.: Committee to evaluate re-appointment of the Head of the School of Physics & Astronomy, 2005-06.
UMN I.T.: Library committee, 2005-present.
Highly ionized diffuse matter, particularly that associated with quasars, supernova remnants and X-ray sources - considered in "non-classical" nebular manner. Other aspects of X-ray sources and also very massive stars.
The nature of "Supernova Impostors": explosions that release as much radiation as a supernova, but leave the star almost intact. The most accessible example is Eta Carinae. SN impostors are far more mysterious than real supernovae, because their basic instabilities are largely unknown.
Expertise: Extremely massive stars, nebular processes, data analysis techniques, special problems. Has usually concentrated on a small number of special objects that give astrophysical information unobtainable anywhere else: Eta Carinae, Crab Nebula, etc.