School of Physics and Astronomy

Astronomy Unit Seminar - Coronal cooling as a result of the Kelvin–Helmholtz instability

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1 February 2019

Time: 2:30 - 3:30pm
Speaker: Andrew Hillier
Venue: GO Jones 610

Recent studies of nonlinear MHD wave dynamics in the solar corona have highlighted how Kelvin-Helmholtz instabilities can be excited by these waves, ultimately leading to turbulence and dissipation of the wave energy (and with it a step towards the holy grail of understanding the heating of the solar corona). These turbulent processes, however, also lead to mixing between the different temperature fluids that exist in the corona, and so the question is: is it turbulence or is it mixing that is more important for understanding the observed thermal evolution of the coronal material driven by these waves.  I will present an approximate analytical model for the mixing by this instability which can be used to estimate the magnitudes of the mixing and heating that can occur. I'll also present an interesting corollary that results on application to some actual observations, i.e. in some cases the instability will result in heating rates are smaller than the radiative loss rates meaning that the instability is likely to result in cooling not heating