Tiny Star Emits Powerful X-ray Flare Ten Times More Intense Than Anything Our Sun Can Produce

Astronomers have spotted a tiny star emitting a huge "super flare" of X-rays ten times more energetic than the most intense flares our sun can produce.

The star, dubbed "J0331-27," has a mass about one-eighth that of our sun's. In fact, due to its relatively low mass, it only just qualifies for being a star.

Stellar objects like these are known as "L-dwarfs" and, previously, scientists thought stars like these were not capable of such high-energy eruptions.

However, the unique super flare in question—recorded by the European Photon Imaging Camera (EPIC) onboard ESA's XMM-Newton X-ray observatory in 2008—is challenging our understanding of these events, according to a study published in the journal Astronomy & Astrophysics.

Flares like these occur when magnetic energy builds up in a star's magnetic field and is suddenly released, causing radiation to be emitted and a rapid increase in brightness.

"This is the most interesting scientific part of the discovery, because we did not expect L-dwarf stars to store enough energy in their magnetic fields to give rise to such outbursts," Beate Stelzer, an author of the study from the Institute for Astronomy and Astrophysics at the University of Tubingen, Germany, and the Palermo Astronomical Observatory, Italy, said in a statement.

Scientists thought that L-dwarf stars would not be capable of producing such powerful flaws because their surface temperatures are much lower compared to most stars, and thus they should lack the required energy in their magnetic fields. J0331-27, for example, has a surface temperature about a third lower than our sun.

As such, the researchers are still puzzled as to how J0331-27 was capable of emitting such a powerful flare.

L-dwarf star, super flare
Artist's impression of J0331-27 emitting the X-ray "super flare." ESA

The team of scientists—led by Andrea De Luca from the Institute of Space Astrophysics and Cosmic Physics, Italy—discovered the super flare in data collected by XMM-Newton over a 13-year-period while looking for unusual phenomena.

While some L-dwarf stars have been recorded emitting super flares in the optical part of the light spectrum, this is the first time that scientists have definitively detected a flare coming from one of these stars in X-ray wavelengths—one of the highest energy forms of electromagnetic radiation.

This suggests that the super flare is coming from high in the star's atmosphere, unlike optical light, which originates deeper in the atmosphere. The next step for the scientists is to find more examples of powerful X-ray flares coming from L-dwarfs in order to learn more about the phenomenon.

"There is still much to be discovered in the XMM-Newton archive," said De Luca. "In a sense, I think this is only the tip of the iceberg."