For the first time, scientists have recorded magnetic waves called Alfvén waves in the photosphere of the sun. This discovery might help astronomers explain the reason behind the solar corona being much hotter than the surface.
The Sun is made of plasma, and thus supports Alfvén waves. There are waves in the plasma where ions move responding to tension due to the magnetic field. Though it was predicted over 50 years ago, this is the first instance where scientists have been able to see then in the Sun.
Thanks to recent observations of the Sun’s photosphere, the lowest layer of its atmosphere, and the region behind the light, astronomers have finally found them.
Alfvén waves are the culprit
Sun’s magnetic field can bundle together and forms long structures known as flux tubes, which can form Alfvén waves. A team of scientists, led by Dr. Marco Stangalini at Italian Space Agency (ASI, Italy), including Queen Mary’s Dr. David Tsiklauri and Ph.D. student Callum Boocock, leveraged ESA’s IBIS to take a closer look at the Sun’s photosphere.
The team validated their findings with the help of magnetohydrodynamic (MHD) simulations, which replicated the complex plasma physics happening at the sun’s surface.
“The observations of torsional Alfven waves made by Marco and his team were remarkably similar to the behavior seen in our MHD simulations, demonstrating the importance of these simulations for discovering and explaining wave generation mechanisms,” said Callum Boocock.
A significant difference in temperature
The new findings offer an important leap towards understanding why the outer solar atmosphere, the corona, has a temperature that is a million degrees hotter than the surface. Alfvén waves could be transporting energy from the photosphere to the corona.
As per a study, the Sun’s outer atmosphere layer can reach temperatures of 1.7 million degrees Fahrenheit. This happens due to ‘campfires’ on the surface of the star. Back in June 2020, the ESA snapped the closest images of the Sun using the Solar Orbiter. The images also showed campfires across the Sun’s surface for the first time.
