Durham part of European Solar Telescope team

By Samantha Simmons

In a collaborative venture involving seven European countries, including the UK, the European Solar Telescope (EST) is set to be the largest solar telescope in Europe when it becomes operational in 2028-29. Durham is represented in this project as part of the UK Universities Consortium (Aberystwyth, Durham, Exeter, Glasgow, Sheffield and Queen’s University Belfast). Located on La Palma in the Canary Islands, the EST will provide solar astronomers with significantly increased observing capabilities that are needed to study the fundamental processes of our closest star and how it impacts our planet.

The Sun, which emits light at a variety of different wavelengths, is observed using a solar telescope. Solar telescopes isolate specific wavelengths in and around the visible light spectrum for analysis. Different wavelengths of light emitted from the Sun provide information on different phenomenon and layers within the Sun and solar atmosphere.

From the specific wavelength selected an image can then be formed and analysed. The instrumentation within the EST will allow for simultaneous observations across multiple wavelengths which will give the EST a much higher efficiency than comparable telescopes. Unlike their celestial cousins, solar telescopes must be equipped with filters to safeguard the optics from the brightness of the Sun, and to allow the Sun to be viewed safely.

When space weather hits the Earth, it has a strong impact on our increasingly technologically reliant society

Though the University of Sheffield leads the UK’s involvement in the EST, Durham’s Centre for Advanced Instrumentation within the Department of Physics will work on the multi-conjugate adaptive optics system. The optics system sharpens the images from the EST up to ten times by correcting for the blurring effect of the Earth’s turbulent atmosphere. This along with the bigger size of the EST, with its primary mirror nearly three times greater than the current largest solar telescope in Europe, provides more detailed images of a higher resolution.

Following on from a three-year survey completed in 2011, estimating the design and construction to cost approximately £170 million, the preliminary design phase of the EST has recently been completed. When the EST receives first light it is set to explore astrophysical processes, solar variability and the impact of solar activity on the Earth.

One way of improving our understanding of solar activity is by investigating the magnetic fields and plasmas within the atmosphere of the Sun. This provides insight into mechanisms underlying solar flares and coronal mass ejections (CMEs) which are factors in determining ‘space weather’. When space weather hits the Earth, it has a strong impact on our increasingly technologically reliant society.

Both solar flares and CMEs are caused when the magnetic field within the Sun contorts and gets ‘tied up’ and is then released like a rubber band. Solar flares are linked to the eleven-year solar cycle of the Sun and occur when magnetic energy builds up in the solar atmosphere before suddenly being released. This causes large explosions from the Sun’s surface emitting intense bursts of electromagnetic radiation, which can accelerate high energy particles that can reach the Earth in about eight minutes.

Though solar flares are faster, CMEs are much more powerful

Though solar flares are faster, CMEs are much more powerful. CMEs are large expulsions of plasma and magnetic field in a single direction from the corona (upper atmosphere of the Sun) which releases charged particles and can take up to three days to reach the Earth. When these charged particles interact with the magnetic field of the Earth, they cause geomagnetic storms. While these geomagnetic storms are welcomed by many as they trigger the captivating auroras, like solar flares CMEs can wreak havoc on telecommunication networks, orbiting satellites and can cause power grid outages.

A better understanding of solar activity and its impact on space weather events will allow more resilient systems to be built, and better predictions of when these space weather events occur. This will allow more warning time for satellites and power grids to be put into a ‘safe mode’ by their operators to avoid damage.

As the European Solar Telescope turns its gaze towards the Sun by the end of the decade, astronomers will have the opportunity to refine solar models by monitoring the Sun’s magnetic activity. As our understanding of the Sun’s activity increases, we will also learn how to better safeguard our world against solar weather events in the future.

Image: IDOM

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