Scientists have been using data collected by NASA's now-defunct Kepler space telescope not only to look for planets beyond the solar system but also to probe their parent stars, which pulsate as they spin, causing variations in brightness.
The Kepler observatory can detect these oscillations, much like it detected dips in target stars' light due to planets passing by, or transiting, relative to the telescope's line of sight.
Working both types of observations, scientists have now found the first multi-planet system that is tilted out of alignment with the host star.
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"When we found this system, it was a major surprise. They didn't form this way," astronomer Daniel Huber, with NASA's Ames Research Center in Moffett Field, Calif., told Discovery News.
The star, known as Kepler-56, is about 45 degrees out of alignment from the orbital plane of a pair of planets, which circle their parent star in 10- and 20 days respectively. Trying to determine what elbowed the planets out from the equatorial plane of their star led Huber and colleagues to a third, non-transiting, massive companion, which could be another planet or a star.