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Our enigmatic sun

The sun is classified as an ordinary, middle-aged star and yet its magnetic field is responsible for some of the most dramatic and energetic phenomena in the solar system, such as solar flares and other eruptions.

This theme, among others, was explored today (Wednesday 13th February, 2002) by Professor Alan Hood as he delivered his inaugural lecture at the University of St Andrews.

Professor Hood, a Professor of Mathematics and a member of the Solar Theory Group, gave the lecture, entitled ‘Our Enigmatic Sun’ to an audience of both internal staff and public enthusiasts.

During his lecture, Professor Hood revealed that later this year a new parallel computer consisting of over 100 processors will be installed to complement the ‘supercomputer’ already in place, to develop models of the sun ‘s magnetic activity. This will allow the group to understand in much greater detail the fundamental physical processes occurring in the solar atmosphere.

Dramatic features such as solar eruptions, whose influence extends from the Sun to well outside the Earth’s orbit, have challenged scientists to develop better scientific models of what is going on inside and around the Sun, although great advances have been made in their understanding of the Sun in recent years.

“As our closest star we can investigate the Sun in much greater detail than any other star. Recent satellite missions have provided a surprising amount of information about how the Sun behaves,” said Professor Hood.

“What is surprising scientists is the amazing amount of activity that is occurring in the corona and it is entirely due to the interaction of the local magnetic field with the coronal plasma.”

“This magnetic activity is closely linked to the number of sunspots, which vary on an approximate eleven year cycle. The maximum number of sunspots occurred in 2001 and the solar activity will decline over the next few years. This solar activity takes several forms including, solar flares, erupting prominences and Coronal Mass Ejections (CMEs). If a CME hits the Earth then the Aurora, or northern lights, can be seen. In addition, large eruptions can permanently disable satellites and many have been lost to date,” he said.

Professor Hood is a member of the Solar MHD (Magnetohydrodynamics) Theory Group at St Andrews – a large group of applied mathematicians who study the Sun using sophisticated mathematical modelling techniques and observational data from spacecraft such as SOHO (located between the Sun and the Earth) and ground- based observatories. The St Andrews group is one of the largest in the world studying in the area of mathematical modelling of solar phenomena and has gained a world-class reputation over the past 20 years.

Solar MHD is the study of the subtle interaction between the Sun’s magnetic field and its plasma interior or atmosphere. The group currently investigate a large number of dramatic solar phenomena including sunspots, coronal heating, solar flares and magnetic instabilities.

ENDS

PICTURE CAPTION: AN IMAGE OF THE SUN TAKEN TODAY. COURTESY OF SOHO/EIT CONSORTIUM. SOHO IS A PROJECT OF INTERNATIONAL COOPERATION BETWEEN ESA AND NASA.

NOTE TO EDITORS: PICS OF DRAMATIC SOLAR PHENOMENA ARE AVAILABLE BY EMAIL. PLEASE CALL GAYLE COOK TO ARRANGE COPIES – CONTACT DETAILS BELOW.

Issued by Beattie Media On behalf of the University of St Andrews

Contact Gayle Cook on 01334 467227, mobile 07900 050103, or email gec3@st-andrews.ac.uk Ref: our enigmatic sun pr 130202 View the latest University news at http://www.st- andrews.ac.uk/extrel/press.htm

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