Friday, April 22, 2005

Dr. Vesa Junkkarinen

"Chemical Abundances in Quasars"  

2:00 pm in room P-148

Abstract:  The abundances of the chemical elements in quasars provide clues to part of the chemical history of the universe. We believe that the extreme luminosity of a quasar is produced by an accretion disk around a supermassive black hole in the nucleus of a galaxy. The gas associated with quasars has been found to be metal rich. The chemical elements heavier than hydrogen and helium are more abundant in quasars than in the gas in our solar neighborhood. Several cycles of rapid star formation in the nucleus of a galaxy will produce metal enriched gas. But the details of the chemical abundances in quasars and how they fit the general pattern of chemical abundances in the universe are still very uncertain. This colloquium will provide a review of what we know and don't know about chemical abundances in quasars.