The team ran millions of simulations, looking for one that reproduced the exact light changes that Kepler observed. Next, Giammichele borrowed a computer simulation technique from her former life as an aeronautical engineer to figure out how the changes in vibrations related to the makeup of the core. The observations provided the highest-precision data ever on tiny changes in a white dwarf’s brightness and, indirectly, its vibrations. But it also monitored white dwarf KIC 08626021, located 1,375 light-years away in the constellation Cygnus, for 23 months. Kepler’s chief aim was to find exoplanets, the worlds orbiting distant stars ( SN Online: 10/31/17). Giammichele and her colleagues used data from NASA’s Kepler space telescope, which watched stars unblinkingly to track periodic changes in their brightness. Astrophysicists can infer a star’s internal structure from the vibrations, similar to how geologists learn about Earth’s interior by measuring seismic waves during an earthquake. These stars change their brightness in response to internal vibrations. Luckily, some white dwarfs encode their inner nature on their surface. “From theory, we have a rough idea of how it’s supposed to be, but we have no way to measure it directly,” says astrophysicist Noemi Giammichele, now at the Institute of Research in Astrophysics and Planetology in Toulouse, France. But the proportion of those elements relative to one another was uncertain.