For the first time, astronomers observed magnetic waves of energy called Alfven waves in the photosphere of the sun. This discovery could help explain why the solar corona is so much hotter than the surface.
The sun is made up of plasma and, like any plasma, should support Alfven waves. These are waves in a plasma in which the ions move in response to the voltage of a magnetic field. First predicted over 50 years ago, astronomers have not yet been able to see them in the sun. But recent observations of the Sun’s photosphere – the lowest layer of its atmosphere and the region that releases the light we can see – have finally found it.
Magnetic fields in the sun can focus and form long structures called flux tubes. These flow tubes can promote the formation of Alfvén waves. A research team led by Dr. Marco Stangalini from the Italian Space Agency (ASI, Italy) with scientists from seven other research institutes and universities, including Queen Marys Dr. David Tsiklauri and Ph.D. Callum Boocock, a Callum Boocock student, used the European Space Agency’s IBIS to carefully monitor the Sun’s photosphere.
Despite previous claims, Alfvén waves have never been found conclusively on the sun before.
The researchers validated their observations using magnetohydrodynamic (MHD) simulations, which are computer simulations of the complex plasma physics on the solar surface.
Callum Boocock, a Ph.D. A student at the Queen Mary School of Physics and Astronomy, said: “The observations of Alfven torsion waves by Marco and his team were remarkably similar to the behavior of our MHD simulations, demonstrating the importance of these simulations in the discovery and explanation of wave-generating mechanisms.”
The findings provide a decisive step towards understanding why the outer solar atmosphere, the corona, is a million degrees hotter than the surface. Something that carries a lot of energy from the photosphere to the corona, and those Alfvén waves could be the culprit.
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