Publication: Physics World; First HAO Author: Philip Judge

Magnetic field lines in the corona

Magnetic field lines are shown extending from the Sun into interplanetary space (a and b) and returning to the solar surface (other panels). Each shaded region shows how small scales are produced from larger-scale motions at the solar surface by phase mixing (panel b), resonant absorption (panel e), and the quasi-static evolution of current sheets as the near ideal MHD attempts to develop tangential discontinuities (panel f). In panels (a) the motions can be thought of as propagating and standing waves, and in panel (f) the motions are slow enough that a quasi-static evolution is envisaged.

Ask a group of astronomers what heats the solar corona and you’ll be surprised by how many different answers you’ll get. Some might say “magnetic energy”. Others “Alfven waves” or “nanoflares”. Yet others will talk about “turbulence”, “ion cyclotron waves” or “magnetic reconnection”. In fact, almost one article about the solar corona has been published per day since 1943.

See Phil Judge's article to read more: The enduring mystery of the solar corona