A starlit sky may look serene, but those stars are actually quivering and quaking; now, researchers have recorded the stellar vibrations of distant stars for the first time. The pulsations reflect changes in temperature caused when roiling heat makes the outer surface of the star vibrate. Portions of the surface expand and cool, while others contract and get warmer [New Scientist].
The initial discovery of oscillations in our Sun in the late 1970’s led to the creation of “solar seismology,” which has since been used to measure the movement and transport of heat around the Sun. Solar seismology led to rapid progress in understanding the Sun’s internal structure, but eventually researchers hit a wall [COSMOS]. For accurate measurements, researchers need a long stretch of uninterrupted observations, which is impossible from ground-based telescopes.
The 2006 launch of France’s Convection Rotation and Planetary Transits (Corot) space telescope gave researchers the tool they needed. The three stars that the researchers focused on in their study, published in Science [subscription required], were all between 100 and 200 light-years from Earth; they are similar to our sun but hotter and more massive. Researchers measured the stars’ light output over a 60-day period and found that while their fluctuations were more dramatic than the sun’s, they were still 25 percent weaker than expected. The disparity suggests that astronomers do not completely understand how energy is transformed – from heat circulation to changes in the density of gas – on stellar surfaces [New Scientist].
Researchers say the field of stellar seismology is just beginning. “The fact that COROT succeeded in probing the interior of sun-like stars with direct measurements for the first time is a huge leap in understanding stars in general,” [researcher Malcolm] Fridlund said. “In addition, this will help us to understand, by comparison, our own sun even better” [SPACE.com]. Researchers hope to gain a deeper understanding of how the sun’s fluctuations in the past may have affected the Earth’s climate, causing ice ages or warmer epochs. The recorded stellar fluctuations are analogous to our own sun’s solar variations, the changes in the sun’s overall radiation output (of which the small blips known as sunspots make up only a tiny part).
DISCOVER: How Long Until We Find a Second Earth?, which details Corot’s search for exoplanets
Image: Aarhus University/S. Frandsen