Astronomers have previously detected superflares from a variety of star types, which
release bursts that have 10 to 10,000 times more energy than the largest solar flare ever detected from our sun. Scientists wanted to know how common these outbursts might be from stars like the sun, those with masses and temperatures similar to our star. Even normal solar flares can damage satellites, endanger astronauts and wreak havoc on electrical grids on Earth, suggesting that superflares might be catastrophic to life on Earth. Until now, few superflares have been detected from sunlike stars. This rarity has hampered detailed analysis of what might cause them to happen. Now, with NASA’s Kepler planet-hunting satellite, researchers have a way to analyze many sunlike stars at once. The scientists monitored about 83,000 sunlike stars over 120 days and detected 365 superflares from 148 of the stars, each lasting one to 12 hours. Slowly rotating solar-type stars were responsible for only 101 of the superflares seen in the sample. This suggests that slowly whirling stars like our sun have superflares much less often than rapidly spinning ones. Somewhat regular fluctuations in the brightness of the superflaring stars hints they all possess large starspots, much larger than the sunspots seen on our sun. This suggests they are caused by magnetic activity of the stars, just as solar flares are linked with sunspots and solar magnetic activity. Rapidly spinning stars are expected to experience more magnetic activity than slower-whirling ones, which likely explains why they have more superflares. Scientists had thought superflares of sunlike stars were caused by magnetic interactions between the stars and so-called hot Jupiters. However, the researchers found that no hot Jupiters were discovered around any of the superflaring stars they studied, suggesting that superflares from sunlike stars are actually only rarely linked with hot Jupiters.