摘要
Supernovae -- the explosions marking the final fates of stars -- are archetypical events of cosmic evolution. Supernova explosions regulate the birth of new stars and they are the source of all the heavy elements in the universe, including those on Earth and in all living systems.
Records of supernova sightings extend to the dawn of history. 24 years ago, astronomers discovered Supernova 1987A, the brightest supernova since Kepler's supernova of 1604 AD. By observing this and other supernovae with modern telescopes of all types, astronomers are gaining an unprecedented understanding of how supernovae work.
The Milky Way is a great cosmic ecosystem, in which new stars are constantly being born from condensations in the interstellar gas, while other stars die as supernovae, recycling most of the gas and enriching it with heavy elements. Out of the material dispersed by these explosions, somewhere else a new star with rocky planets can form. The supernova explosions drive violent motions in the gas and regulate the formation of new stars.
With powerful modern telescopes, astronomers can now observe supernovae in galaxies so distant that we see them as they were when the universe was less than 1/4 its present age. These distant supernovae can be used as beacons to measure the history of the expansion of the universe and to probe the universe at the time when the first stars and galaxies are born.
报告人简介
Richard McCray received his Ph.D. in theoretical physics from the University of California at Los Angeles in 1967. He was a Postdoctoral Fellow at Caltech (1967-68) and an Assistant Professor at the Harvard College Observatory (1968-71). In 1971, he moved to the University of Colorado at Boulder, where he is now George Gamow Distinguished Professor of Astrophysics. He has held visiting positions at the NASA Goddard Space Flight Center, Beijing University and Nanjing University, the Space Telescope Science Institute, Columbia University, and the University of California at Berkeley.
In 1989 Prof. McCray was elected to National Academy of Sciences. In 1996 he was appointed Concurrent Professor of Astronomy at Nanjing University. In 2002 he was awarded the National Science Foundation Director's Award for Distinguished Teaching Scholars.
Prof. McCray's research is in the theory of the dynamics of the interstellar gas, theory of cosmic X-ray sources, and, most recently, the theory and observations of Supernova 1987A. Prof. McCray is also engaged in observations of these phenomena with various spacecraft, including the Hubble Space Telescope and the Chandra X-ray Observatory.
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