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The Sun occasionally produces flares — powerful bursts of energy that last from minutes to hours. Most are random, like raindrops hitting a roof. But sometimes one flare seems to ignite another: the second begins almost immediately after the first, even though they occur in different locations. Astronomers call these sympathetic flares.

For a long time, such paired flares were observed only on the Sun. On other stars, they were hard to detect reliably: stars are too far away, and flares can be faint and overlap in time. A team of researchers created a new algorithm that can distinguish even closely spaced flares. They applied it to data from the TESS space telescope, which monitors the brightness of hundreds of thousands of stars.

In total, the scientists found about 220,000 flares on 16,000 stars, most of which are red dwarfs — small, cool stars. They looked at how often flares follow one another. If flares were completely random, the intervals between them would follow a specific distribution. But they found more short intervals than expected. This means that some flares trigger their neighbors.

This discovery shows that the Sun is not unique: small stars behave similarly. Perhaps the mechanism that triggers chains of flares is common to all such stars. Now astronomers can study it on thousands of objects, not just our own star.

Original abstract

as written by the authors arXiv:2602.20311

Most flares on the Sun occur at random, but there is a small percentage of "sympathetic flaring" -- the triggering of one flare by another. Previously there had been no widespread confirmation of sympathetic flares on other stars. In this work, we developed a new flare detection algorithm that is sensitive to closely-separated and overlapping stellar flares. We applied it to TESS data and discovered ~ 220,000 flares on ~ 16,000 stars, the majority of which are M-dwarfs. The wait time distribution between flares demonstrates an excess of closely-separated flares, relative to expectations from a Poisson process. We attribute this to sympathetic flares, occurring at a rate of between 4% and 9%, which matches the rate seen on the Sun. Our result is the first statistically robust detection of sympathetic flares on other stars, demonstrating a commonality between the Sun and low-mass stars.