Understanding Alfven Wave Heating of the Solar Corona through Observations and Experiments

ABSTRACT

The solar corona is the outer layer of the Sun, which is visible from Earth during solar eclipses. The corona has a temperature of over one million Kelvin. This is much greater than that of the underlying photosphere, which is only about 6000 K. Explaining the heating of the corona has been a longstanding problem in astrophysics. One theory of coronal heating is that the energy is carried into the corona by Alfven waves, which then dissipate transferring this energy into particle heating. Spectroscopic observations show that such waves do carry sufficient energy to heat the corona and are damped fast enough to be an efficient heating mechanism. It remains to understand the damping of the Alfven waves. We are studying this question through solar observations and laboratory experiments. I will present some recent results including observations suggesting that Alfven wave damping is promoted by interactions with acoustic waves in the corona and the first experimental measurements of Alfven wave reflection from plasma inhomogeneities comparable to those found in the solar corona.

BIOGRAPHY

Michael Hahn is a Senior Research Scientist in the Columbia Astrophysics Laboratory at Columbia University. His research aims to understand the heating of the solar corona and the sources and acceleration of the solar wind. His research group is addressing this problem through analysis of solar observations; laboratory experiments in plasma physics to study the basic physical processes that happen at the Sun; and experiments in atomic physics to improve the precision of spectroscopic diagnostics. He received his B.S. in Physics from Carnegie Mellon University in 2005 and his Ph.D. in Applied Physics from Columbia University in 2009.