The insides of stars are a boiling mess. The turbulent motion of superhot plasma causes the magnetic field coursing within to cycle between periods of low and high intensity—resulting in sunspots and solar flares. But scientists never knew what controlled the length of these cycles, which last about 11 years in our own sun. So one team of astronomers used data from the Gaia space observatory to simulate the interiors of solar-type stars, which are similar in mass and age to our own sun. In particular, they wanted to answer a burning question: Why do other solar-type stars have such wildly varying solar cycles? For example, one such star—known as Kappa Ceti, in the Cetus constellation—has cycles that last 5.6 (Earth) years. After looking at more than 25 magnetic cycles, researchers found that the length of each star’s cycle is related to its rotation rate and brightness, they report today in Science. Faster spinning, but fainter, stars have longer cycles. The results may help scientists better understand solar magnetic fields, and they should lay to rest one long-standing uncertainty—that our sun was not a solar-type star!
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