Science Digest Chalk Talk: The Solar Orbiter Project

Prof. David Williams from the European Space Agency (link)

Abstract

“In this informal discussion, I will briefly introduce my activities in the Solar Orbiter project at the European Space Agency (ESA).

I look at the Sun in ultraviolet light, where it's covered in rope-like filaments, tenuous bright magnetically-shaped loops and puzzlingly hot ionised gas (plasma). Filaments are truly fascinating structures hovering in the corona, at the interface between low and high states of ionisation, density, plasma β and temperature. This begs us to understand not only their structure, but also their creation and often explosive destruction.

Solar active regions, areas of intense and often complex magnetic fields on the Sun, play host to some filaments. But they are also interesting for another reason: in the unusually hot solar corona, these are the hottest sites of all, and they can release energy violently as well as constantly from the reordering of these magnetic fields. This ongoing magnetic furnace can throw our usual easy rules-of-thumb about plasma behaviour out the window. Understanding how plasma is heated, and whether it behaves like a normal Maxwellian "gas", or has a long-lasting population of high-energy particles, is something we can probe through UV and X-ray spectroscopy (something Solar Orbiter will really help us to do).”