Launched in March 2009, NASA's Kepler observatory has become synonymous with the search for extra-solar planets. But that's not all it's been doing up in space. The spacecraft has also been recording the gentle pulsations of stars—the small variations in their brightness caused by sound waves throbbing outward from the stellar core to the surface (seen in the yellow star in illustration). In the latest issue of Science, researchers report measuring these pulsations for some 500 sun-like stars, which is enabling statistical studies of stellar characteristics like mass, radius and age and test models of stellar evolution. In another paper in the same issue, a different research team reports using Kepler data to detect a system of three stars, which includes a red giant star and two red dwarfs. Although astronomers thought that the red giant would show sun-like oscillations caused by waves from within, they found that the star's pulsations were being driven by the waxing and waning of gravity from the orbital motion of the two red dwarfs. Researchers hope to use these observations to gain new insights into the formation of stellar systems, as well as the evolution of stars.
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