Forecasting the Sun’s future

Astronomers sifting through data from the Kepler telescope have discovered waves inside a star so deep that they reach the core – a finding which forecasts the future of our own Sun

Kelper detects stellar waves which reach the centre of a red giant Credit: SAp/CEA

Stellar oscillations were known to exist in stars, but up until now, scientists had only observed them in the outer part of the star. At a certain depth – hundred thousands of kilometres deep – the stellar material gets too dense to penetrate so the waves are bounced back to the surface.

However, scientists from the Kepler Asteroseismic Science Consortium (KASC) observed out of key stellar oscillations in a giant red star. When they compared these different waves to theoretical models, the researchers realised they reached the core.

“Having a view into the core of these red giants will teach us exactly what will happen to our Sun when it grows older,” said Paul Beck, a PhD student at Leuven University in Belgium.

Our Sun will become a red giant in about 5 billion years – by that time it will be about 10 times its current size, 50 times brighter and will have changed from yellow to red.

Stellar oscillations manifest themselves as patches where the temperature changes slightly, more or less periodically over time. This causes tiny variations in the brightness of stars which have travelled for hundreds of years through empty space which can be detected by NASA’s Kelper Telescope.

“Astronomers all over the world are taking part in this huge effort to exploit Kelpler data to better understand the interiors of stars,” said Hans Kjeldsen, coordinator of KASC. “The measurements provided by Kelper are so incredibly precise that we see things we never saw before. It’s like travelling in a whole new world.”