Eric R. Priest

The 2017 Hannes Alfvén Medal is awarded to Eric R. Priest for his fundamental contribution to the understanding of the mathematical complexity and physics of magnetic reconnection and the magnetic coupling of the convection zone with the solar atmosphere.

Eric Priest is a world-leading solar physicist dealing with the Sun’s plasma. He has done seminal work on a number of topics related with the magnetohydrodynamic (MHD) aspect of 2D and 3D magnetic reconnection, coronal heating, and the importance of the newly emerging magnetic flux in the initiation of a flare and the establishment of the coupling of the convection zone with the solar atmosphere. Priest used his superb mathematical skills and physical intuition to extensively analyse numerous key mechanisms of 2D and 3D magnetic reconnection. In his work, he emphasised the role of the presence or the absence of null points inside the unstable coronal structures. This particular point has been of huge significance in our understanding of the magnetic structures formed in the solar corona. His work advanced the general theory of ‘fast’ magnetic reconnection and in particular the role of the external boundary conditions in determining the reconnection rate. Starting almost 40 years ago, he wrote many seminal articles clarifying the basic structure of the fast reconnection model and continues this work today with numerous collaborators. Today, many scientists use ideas based on the null points and near separatrix surfaces, going back to Priest’s work on 3D reconnection, to identify the location of the reconnection volume. A culmination of this fundamental research was his publication together with Terry Forbes of the monograph Magnetic Reconnection: MHD Theory and Applications. Another important topic in which Priest has played a key role was his search for the most important physical processes behind coronal heating. He put forward, with his collaborators, three very important ideas: the phase mixing of Alfven waves, reconnection driven by ‘coronal tectonics’, and smallscale dissipation as a result of Taylor relaxation. Most of these ideas have been widely used by the solar physics community in recent years. Priest’s long and fruitful collaboration with Jean Heyvaerts explored the role that the magnetic flux emerging from the convection zone plays in triggering flares and solar eruptions. This idea became the current paradigm for the role of the emerging magnetic flux in solar activity, and it became the key process that establishes the strong coupling of the convection zone with the solar atmosphere. For his vital contributions to solar-terrestrial physics, Eric Priest richly deserves the EGU Hannes Alfven Medal.