Dr. Donald E. Osterbrock
Professor Emeritus of Astronomy and Astrophysics
Donald Osterbrock's main line of research has been observational work on the gas in active nuclei of galaxies--especially radio galaxies, Seyfert galaxies, and X-ray galaxies--and its interpretation. He and his research associates have also been observing quasars, as well as galaxies with weaker emission lines or lower-ionization emission lines, to find the relationship among these objects. They are all related members of "one- family," but at different luminosities, containing different amounts of dust and gas, and perhaps in different stages of their evolution. There is strong observational evidence that interactions, perturbations, and mergers of galaxies are connected with activity in their nuclei. Osterbrock is now working on the interpretation of these data in terms of the formation and evolution of active galactic nuclei.
The best working hypothesis is that many, if not all, "normal" galaxies contain black holes in their nuclei, which without new fuel in the form of gas with very nearly zero angular momentum are quiescent. Refueled in an interaction, however, they can pass through the star formation phase to, in some cases, the active galactic nucleus phase. Connecting these qualitative observational statements with the results of quantitative but schematized theoretical ideas and numerical computation is the most important problem in current research on active galactic nuclei. Graduate students who have participated in recent years in obtaining the spectra with the CCD spectrograph on the 3-meter Shane Telescope include Sylvain Veilleux, Hien Tran, and Andre Martel.