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Joint Astrophysics Colloquium
Eric Feigelson Penn State University X-ray astronomy is a relatively new field studying high energy phenomena, such as million-degree plasmas, in celestial objects. The Chandra X-ray Observatory, launched by NASA in mid-1999, provides advanced technologies for X-ray studies with superbly polished mirrors for high-resolution imaging, solid state detectors and grating spectroscopy. The historical development of one topic in X-ray astronomy is outlined: the discovery that solar-like stars produce greatly enhanced X-ray emission just after their birth compared to the modest levels seen during their long-lived main sequence phase. The X-rays are produced by explosive magnetic reconnection events at or near the stellar surface. The X-rays may have important astrophysical effects on their environment, ionizing otherwise neutral gas in the circumstellar disks and molecular cloud. This in turn may elevate the role of magnetohydrodynamical phenomena and thereby affect the future formation of stars and planets.
Friday, October 19th 2000, 12:30 (UdM) |