Events at Physics

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Events on Tuesday, April 27th, 2010

Chaos & Complex Systems Seminar
Title to be announced
Time: 12:05 pm
Place: 4274 Chamberlin Hall
Speaker: Ananth Seshadri, UW-Madison, Dept. of Economics
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Astronomy Colloquium
The Nova Outburst: Evidence for a New Paradigm?
Time: 3:30 pm - 5:00 pm
Place: 3425 Sterling Hall
Speaker: Dr. Robert Williams, STSci
Abstract: Spectroscopic observations of novae date back a century and the fundamental nature of the outburst has been understood for 50 years. Yet, recent observations suggest a possible significant modification to the standard nova paradigm. A high-resolution spectroscopic survey of novae has revealed short-lived heavy element absorption systems near maximum light consisting of Fe-peak and s-process elements. The spectroscopic evolution of novae is interpreted in terms of two distinct interacting gas systems in which the bright continuum is produced by the outburst ejecta but absorption and emission lines originate in gas ejected by the secondary star in a way that could explain dust formation and X-ray emission from novae. The absorbing gas is circumbinary and it pre-exists the outburst. Its origin appears to be mass ejection from the accretion disk or secondary star, and it might initiate novae outbursts.
Host: Professor Richard Townsend
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