Paris, April 19 : Data obtained from the ESA/NASA spacecraft SOHO (Solar and Heliospheric Observatory) has shown that powerful quakes ripple around the Sun as a result of powerful solar flares that explode above its surface.
According to a report from ESA (European Space Agency), these observations give solar physicists new insight into a long-running solar mystery and may even provide a way of studying other stars.
The outermost quarter of the Sun's interior is a constantly churning maelstrom of hot gas. Turbulence in this region causes ripples that criss-cross the solar surface, making it heave up and down in a patchwork pattern of peaks and troughs.
The joint ESA-NASA spacecraft SOHO has proved to be an exceptional spacecraft for studying this phenomenon.
Discovering how the ripples move around the Sun has provided valuable information about the Sun's interior conditions. A class of oscillations called the 5-minute oscillations with a frequency of around 3 millihertz has proven particularly useful.
According to conventional thinking, the 5-minute oscillations can be thought of as the sound you would get from a bell sitting in the middle of the desert and constantly being touched by random sand grains, blown on the wind.
But what Christoffer Karoff and Hans Kjeldsen, both from the University of Aarhus, Denmark, saw in the data, was very different.
"The signal we saw was like someone occasionally walking up to the bell and striking it, which told us that there was something missing from our understanding of how the Sun works," said Karoff.
So, they began looking into the mystery and discovered an unexpected correlation with solar flares. It seemed that when the number of solar flares went up, so did the strength of the 5-minute oscillations.
"The strength of the correlation was so strong that there can be no doubt about it," said Karoff.
According to Karoff, the correlation is not the end of the story. Now the researchers have to work to understand the mechanism by which the flares cause the oscillations.
"We are not completely sure how the solar flares excite the global oscillations," he said. In a broader context, the correlation suggests that, by looking for similar oscillations within other stars, astronomers can monitor them for flares.