Professor J. Craig Wheeler, a leading supernova expert, delivered the second Maurer Lecture in Physics on Thursday, February 15 in Giffels Auditorium. The Maurer Lecture Series was established to honor Dr. Robert D. Maurer's contributions to physics. Dr. Maurer who is an alumnus of the Department is the co-inventor of the first telecommunication grade optical fiber.
Professor Wheeler's public lecture, entitled "Breaking the Solitude: Explosions in the Night Sky," was concerned with supernovae explosions. Supernovae are relatively uncommon astronomical events. Supernovae go off in galaxies like ours about once every 25 years. Most of them cannot be seen because they are hidden by the dust and the disk of our galaxy, the Milky Way. Occasionally though these explosions can be bright enough to be seen by the naked eye. The Crab Nebula is the remnant of one such supernova explosion in the Milky Way galaxy which was first observed on Earth in 1054. It was reportedly clearly visible in the daytime for more than two weeks. The last supernova, spotted in 1986, took place in the Large Magellanic Clouds, the neighboring galaxy to the Milky Way.
Wheeler traced the life history of a star, describing various stages in its evolution and its destiny. Sufficiently massive stars end up as supernovae. Supernovae are enormous explosive events that represent not only the catastrophic deaths of stars but also the production of new forms of matter. Nearly all the elements required to make life possible are formed in these stellar cauldrons. Carbon, nitrogen, and oxygen are the most precious of these elements. Some of the supernovae explosions also produce fantastic new forms of matter such as neutron stars and black holes. Wheeler's lecture explored the story of some special supernovae and the impact of supernovae in our interconnected universe.
Wheeler's second talk, delivered the next day on February 16 in the Physics Department, was entitled "Black Hole X-ray Novae." It was aimed at a technical audience. Wheeler said that new black hole candidates have been discovered at the rate of about one per year for the last half-dozen years. Unlike the famous Cygnus X-1, these systems do not represent black holes orbiting massive stars and do not shine steadily. Rather, they are black holes orbiting very small mass stars. They lie dormant for decades before emitting a burst of radiation throughout the electromagnetic spectrum from radio to gamma rays. Wheeler said that whereas there may be only one Cygnus X-1 in our whole galaxy, there are probably a thousand of these black hole novae, making them the most common form of binary black holes. Two of them have recently displayed apparent "superluminal expansion" as radio sources, making the analogy to quasars very close.
Professor Wheeler is the Samuel T. and Fern Yanagisawa Regents Professor of Astronomy at the University of Texas at Austin. He has published more than 175 scientific papers and a novel, and has edited two books. A popular science lecturer, Wheeler has received many awards for his teaching. Wheeler received his B.S. from MIT and his Ph.D. from the University of Colorado. Before joining the University of Texas he held appointments at Caltech and Harvard. He was a visiting fellow at the Joint Institute for Laboratory Astrophysics (JILA), the Japan Society for the Promotion of Science, and a Fulbright Fellowship in Italy. He has served on a number of advisory committees, including the National Science Foundation (NSF) and the National Aeronautics and Space Administration (NASA), the Warner-Pierce Prize Committee, the Tinsley Prize Committee of the American Astronomical Society, and the organizing committee of the International Astronomical Union Commission on Stellar Constitution.*