Solar and Magnetospheric Magnetohydrodynamics and Plasmas: Theory and Application

The Solar and Magnetospheric Theory Group (SMTG) of the University of St Andrews will work on the fundamental physical processes occurring in the Sun's atmosphere and planetary magnetospheres that help to address the key STFC Roadmap question "How does the Sun influence the environment of the Earth and the rest of the Solar System?" For example, the proposed work addresses questions, such as:
i) How do sunspots and active regions (regions of strong magnetic fields) form, evolve and decay? ii) Why is the Sun's outer atmosphere (the corona) over 100 times hotter than its visible surface? iii) What causes the observed waves in the Sun's atmosphere and the Earth's magnetosphere? iv) How does the Sun's magnetic field evolve over many years and how does it interact with the Earth? v) How does a 3D magnetic field change its configuration? vi) How are charged particles accelerated during solar flares and eruptions?
Finding answers to these key questions calls for a range of expertise. The SMTG is excellently positioned to answer these questions, since we study a wide variety of physical phenomena using mathematical modelling (a combination of fundamental theory, analytical models, computer simulations, forward modelling and observations). This is exactly what is needed, i.e. a mixture of detailed modelling methods and a comparison between observations from several satellite missions and the theoretical models. The topics we will investigate, using plasma theory, are: i) the emergence of magnetic fields from the solar interior and their subsequent evolution, the formation of cool dense prominences and the evolution of the global magnetic field of the Sun, ii) the propagation and dissipation of magnetohydrodynamics (MHD) waves, iii) the physical 3D mechanisms by which magnetic fields change their connectivity, releasing excess energy and how particles are accelerated to high energies, iv) the physical mechanisms responsible for keeping the solar atmosphere much hotter than the solar surface (atmospheric heating), v) the evolution and topology of the global coronal magnetic field, vi) the coupling of the 3 distinct magnetospheric MHD waves and the physics of the coupling of planetary magnetospheres to their ionospheres.

These phenomena obey physical laws that can be expressed as non-linear partial differential equations. However, what makes them distinct is that different phenomena require different dominant terms. Hence, the physical processes and the plasma response will be different in each case. For example, magnetic reconnection requires electrical resistance, but MHD waves in general do not. Gravity is important in flux emergence and prominence formation, but for magnetic reconnection it is not. Particle acceleration in solar flares and the magnetosphere requires a kinetic (particle) description, while many of the other research areas do not. It is the rich complexity of the non-linear equations that makes them hard to solve and to determine which key physical processes are responsible for each event.

A very important research tool is High Performance Computing. A research problem can be split up into smaller parts that are run on different processors at the same time (in parallel). Hence, with 256 processors a job that would require 10 years on single processor, will be completed in a few weeks.

We address key issues in the STFC Science Roadmap. However, a detailed understanding of the physics of our research topics is important not only for the Sun, solar-like stars and space weather, but also for understanding such diverse astrophysical processes such as star formation in giant molecular clouds, the evolution of astrophysical discs around stars, black holes and in Active Galactic Nuclei, and the physics of winds and outflows from stellar to extragalactic scales.

Who will benefit from this research and how?

While the main impact of the proposed research will undoubtedly be academic in nature, there will also be significant economic and societal impact. The skills required for research in theoretical solar physics means that our group is continually producing people skilled in mathematical modelling, computational (including parallel computing) methods, visualisation techniques and logical thinking for non-academic professions. There is a universality of techniques required to solve cutting-edge scientific problems in MHD that means our group members are highly sought after. An example of inter-disciplinary research is given by the EU grant for "Model-based preclinical development of anti-tuberculosis combinations". Using computational techniques used in MHD research, work is being undertaken in understanding how to treat tuberculosis by using combinations of drugs.

Nearly 40 former group members have gone on to academic positions and over 55 former group members have flourishing careers outside academia. Thus, we are enhancing the UK research capacity as well as the knowledge and skills of businesses and organisations. Several former PhD students have joined the Atomic Weapons Establishment (Aldermaston) and GCHQ, where their computational skills are potentially improving national security. Former group members formed the scientific consultancy firm, Fluid Gravity Engineering and use their computational skills to solve a wide variety of problems. Some of their recent work involves modelling the re-entry of space vehicles back into Earth's atmosphere and, together with FGE, we hosted an ESA conference on this topic (RHTG6) in 2014. FGE are regular recruiters of our PhD students.

Our public lectures and presentations at various science fairs have helped to increase public awareness in the importance of our research. The ready access to the latest images and movies of the solar atmosphere is extremely useful. When the public can actually see observations on their smart phones within seconds of the images being made, they are always excited. In another example, Professor De Moortel gave the Rosalind Franklin lecture at the British Science Festival 2014. This so inspired a member of the audience that they made a new knitting pattern and a cushion as a Christmas present! Our visits to both primary and secondary schools have helped to enthuse students to study science, in general, and physics and mathematics, in particular. The Space Camp and Sutton Trust summer schools are particularly popular with primary and secondary pupils and help to encourage pupils to study STEM subjects. SMTG staff have been taking part in these schools since 2008. The Sun-Trek (see sun trek guide example) and History of Mathematics websites (for example see mathematical astronomy pages) are fantastic online solar and astronomy resources that appeal to both children and the wider public.

On the academic impact front, we have organised many conferences over recent years (for example, Hinode 6 in August 2012, NAM July 2013, RHTG6 in November 2014). We will be organising the SFTC Solar System Summer School in 2016. Our research has made an impact on the astronomy community with recent Royal Astronomical Society awards. The UKMHD Consortium, led by St Andrews was awarded the 2013 Group Achievement Award for Geophysics and Professor Hood was awarded the 2015 Chapman Medal.