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Speaker: George A. Doschek, Space Science Division, Naval Research Laboratory
Topic: The Atmosphere of the Sun and What Happens in It
Time and Location: 1:00 PM, with Q&A to follow; in a 1st floor conference room at the American Center for Physics (www.acp.org), 1 Physics Ellipse, College Park, MD — off River Rd., between Kenilworth Ave. and Paint Branch Parkway.
Abstract: The Sun’s atmosphere has been a mystery since it was discovered in the early 1940s that the unidentified coronal emission lines seen during solar eclipses were due to highly ionized atoms, implying a high coronal temperature on the order of a million degrees. No one knows even now what exactly causes the high temperatures. Later, the solar wind was predicted and discovered and the atmosphere of the Sun is now known to extend out to the outer boundaries of the solar system. Within the atmosphere extraordinary violent plasma events occur such as solar flares and coronal mass ejections that can produce temperatures up to about 25 million degrees and multi-MeV particles.
Because of our increasing electronic dependence on near-Earth spacecraft and ground power sources, and the propagation of radiation and highly energetic particles from the Sun to the Earth, the Sun is a potential source of a major electronic disaster. Studying and mitigating the effects of the Sun’s atmosphere on the Earth is the subject of Space Weather. In this talk I will focus on what we have learned about the solar atmosphere from space, particularly observations in the extreme-ultraviolet and X-ray regions, and discuss some of the possible causes of coronal heating and the production of flares and coronal mass ejections. All of the material I will discuss comes from currently orbiting state-of-the-art solar observatories.
Biography: George Doschek is currently a Research Physicist in the Space Science Division of the Naval Research Laboratory (NRL). He received a B.S. in Physics in 1963 from the University of Pittsburgh and a Ph.D. in physics in 1968 from the University of Pittsburgh. He was Branch Head of the Solar-Terrestrial Relationships Branch in the Space Science Division at NRL from 1979 until January 2011. Between 1970 and 1979 he was a Research Astrophysicist at NRL, and between 1968 and 1970 he was an E.O. Hulburt Fellow at NRL.
He is a member of the American Astronomical Society, the American Geophysical Union, the International Astronomical Union, and is a Fellow of the Optical Society of America. He is an author of over 300 research papers on solar physics and X-ray and extreme-ultraviolet spectroscopy. His research areas are solar physics, atomic physics, and solar physics spectroscopic space instrumentation. He has analyzed data from many astrophysical space missions and has been a key player in the design and construction of solar space experiments. He is currently the Principal Investigator to NASA for the multi-national United Kingdom Extreme-ultraviolet Imaging Spectrometer on Hinode.