SPACE AND COSMIC RAY PHYSICS SEMINAR

University of Maryland
Atlantic Building, Room 2400
4:30 PM Monday, December 5, 2016
Coffee, Tea & Snacks 4:15-4:30 PM

James A. Klimchuk
Goddard Space Flight Center

Current Sheet Proliferation, Turbulence, and the Heating of the Magnetically-Closed Solar Corona

At several million degrees, the solar corona is three orders of magnitude hotter than the underlying solar surface. Explaining this mystery is one of the great challenges in space science. It is generally accepted that coronal heating takes the form of impulsive "nano flares" but the origin of these nanoflares remains an open question. Although they likely involve magnetic reconnection, a comprehensive picture of the complex chain of events has yet to be established. I will explain why we can expect a proliferation of current sheets in the corona due to the constant stirring of the magnetic field by random photospheric motions. The sheets go unstable, leading to temporary bursts of turbulent activity and associated heating. Millions of these events happen every second across the Sun. I will explain why this picture is fundamentally different from traditional turbulence, which has also been proposed as a mechanism for heating the magnetically-closed corona. I will emphasize the importance of understanding the onset conditions for magnetic reconnection.