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22 January 2013

Scientists to explore the Sun

Images show million-degree magnetic loops arching high into the solar corona as viewed in X-rays by NASA's Solar Dynamics Observatory. Both are courtesy of the NASA SDO science teams.

Researchers from the University of Dundee have been awarded more than £750,000 for a project that seeks to further our understanding of how the Sun works.

The aim of the work is to understand the basic physical processes that go on in plasmas on the Sun and throughout the Universe. In this project they will particularly focus on the solar corona, the outer atmosphere of the Sun. Magnetic loops in the solar corona (shown in the in the image attached), solar flares and coronal mass ejections, are among the phenomena that scientists still cannot fully explain.

Plasma, an ionised gas, clings to magnetic fields in the Sun's atmosphere. This means that the magnetic loops in the atmosphere can be seen by high-powered telescopes due to the radiating plasma. The images these telescopes capture show that the plasma on the magnetic loops has temperatures of more than a million degrees, far higher than that of the 5800C surface of the Sun.

The Magnetohydrodynamics group within the University's Division of Mathematics have received £765,000 from the Science and Technology Facilities Council for the three-year 'Complex Magnetic Fields: An Enigma of Solar Plasmas' study.

The grant will fund research time for the group members - Professor Gunnar Hornig, Dr David Pontin, and Dr Antonia Wilmot-Smith - as well as two new full-time Postdoctoral posts at Dundee. A further £68,000 has been awarded to the group's colleague Dr Anthony Yeates at the University of Durham.

Finding out why the loops are so much hotter than the solar surface is a key of the aims of the work, according to Professor Hornig.

"The main focus of this research are these magnetic fields that arch up into the atmosphere from below the surface of the Sun and back down again," he said.

"It is really surprising that with distance from the core of the Sun the temperature drops until it's relatively cool at the surface but then increases dramatically such that coronal loops have multi-million degree temperatures. We don't know why these loops are so hot, why they occur in the way and number they do, and this is what we endeavour to discover."

Professor Hornig says that understanding how the Sun works, and the structures we see on it, will broaden our knowledge of the whole solar system, including our planet. It may help to resolve some of the challenges that scientists have battled with for decades, or even centuries, and prove to have practical benefits for everyday life.

He continued, "Humans have always been interested in understanding their environment, and the Sun is part of our wider environment. One thing we do know about these coronal loops is that they organise themselves according to a pre-determined principle, similar to how frost forms in fantastic patterns on window.

"Learning more about the self-organisation of magnetic fields on the Sun means we will gain more understanding of the principle of self-organisation in our more immediate environment.

"Another aspect to the research is to try and understand the behaviour of magnetised plasmas in general. This is of interest, not only for astrophysics, but also fusion physics. In fusion, we try to capture the same process that heats the Sun on earth in machines that encase plasma in a magnetic field and they try to make fusion.

"This is a long term effort which started about 50 years ago or so. The same type of problems that have so far prevented people from building a working fusion reactor are also affecting plasma on the Sun. So, by studying this, we also improve our understanding of how fusion plasmas work."

Another aspect of the Sun's behaviour the group will look at is coronal mass ejections, explosive events in which billions of tonnes of solar plasma are thrown into space.

Depending on the direction in which it is thrown a mass ejection may be on a collision course with the Earth as it moves through interplanetary space. It is when such a mass crashes into the Earth's magnetic field that the Northern and Southern Lights occur. Less welcomingly, it can also cause problems for spacecraft, satellites, and high-flying airplanes. Blackouts in power distribution systems and corrosion of oil pipelines are other potential side-effects of what is known as "space weather".

"The sun is a constant source of plasma, which it pumps out into space," explained Dr Wilmot-Smith. "At some point, the Earth is affected as these eruptions send out matter which can interact with its magnetic field.

"When this happens it's like an electromagnetic version of an earthquake taking place so understanding how the Sun affects space weather has a direct impact on all of our lives. If we can predict when these things are going to happen we could plan ahead and give warning of these dangerous events. That's one of the long-term goals of this research."

Notes to editors:

About the STFC
The Science and Technology Facilities Council is keeping the UK at the forefront of international science and tackling some of the most significant challenges facing society such as meeting our future energy needs, monitoring and understanding climate change, and global security.

The Council has a broad science portfolio and works with the academic and industrial communities to share its expertise in materials science, space and ground-based astronomy technologies, laser science, microelectronics, wafer scale manufacturing, particle and nuclear physics, alternative energy production, radio communications and radar.

STFC operates or hosts world class experimental facilities including:

  • in the UK: ISIS pulsed neutron source, the Central Laser Facility, and LOFAR. STFC is also the majority shareholder in Diamond Light Source Ltd
  • overseas: telescopes on La Palma and Hawaii

It enables UK researchers to access leading international science facilities by funding membership of international bodies including European Laboratory for Particle Physics (CERN), the Institut Laue Langevin (ILL), European Synchrotron Radiation Facility (ESRF) and the European Southern Observatory (ESO).

STFC is one of seven publicly-funded research councils. It is an independent, non-departmental public body of the Department for Business, Innovation and Skills (BIS).

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