Mysterious High-frequency Waves Swirling On The Sun

 

A team from New York University's Abu Dhabi Center for Space Science analyzed 25 years of space and ground-based observations of energy waves from our host star. High-frequency waves swirling on the sun have left scientists confused, as the unexpected bursts of energy are moving at speeds that defy explanation.

They discovered a new set of waves moving in the opposite direction of the sun's rotation, inexplicably travelling faster than was theoretically possible.

These waves appear as a pattern of vortices, in a swirling motion, on the surface of the sun and move at three times the speed of other types of waves on the star.

Known as high-frequency retrograde (HFR) waves, they provide unprecedented insight into the inner workings of a star, and could one day lead to new types of physics, as follow up studies try to explain how they can be so fast.

The interior of the sun, like other stars of its type, cannot be imaged by conventional astronomy, whether it be optical, x-ray or infrared techniques.

This means scientists have to rely on interpreting the surface signatures of a variety of waves of light, in order to understand what is happening deep inside.

These new High-Frequency Retrograde waves, named because of their counter-direction, may yet be an important puzzle piece in our understanding of stars.

Complex interactions between other well known waves and magnetism, gravity or convection could drive the HFR waves at the unexpected speed, the team predict.

'If the HFR waves could be attributed to any of these three processes, then the finding would have answered some open questions we still have about the sun,' said research associate and study author, Chris Hanson from NYU.

'However, these new waves don't appear to be a result of these processes, and that's exciting because it leads to a whole new set of questions.'

By studying the sun's interior dynamics - through the use of waves - scientists can better appreciate its potential impact on the Earth and other planets.

'The very existence of HFR modes and their origin is a true mystery and may allude to exciting physics at play,' said Shravan Hanasoge, a co-author of the paper. 'It has the potential to shed insight on the otherwise unobservable interior of the sun.'

It comes under a relatively niche area of astronomy, known as helioseismology, which relies on the study of acoustic waves seen in the sun.

This is similar to the study of waves on Earth, that can predict Earthquakes.

With the sun, studying these waves has been used to understand more about its interior rotation and structure - which would be impossible using direct observation techniques.

'We were able to detect equatorially antisymmetric vorticity waves, propagating retrograde at three times the phase speeds of Rossby–Haurwitz waves of the same wavenumber,' the authors wrote.

This is referring to a new type of wave that swirls in the opposite direction to the rotation of the sun, and moving three times faster than other wave types.

This can't be explained by standard hydrodynamic mechanisms, the team explained, suggesting new physics might be at play in the rarified, intense interior of stars like our sun.