Astrophysicists have determined the frequency of super flares occurring on sun-like stars.

Our Sun is a star with quite a high level of activity. To see this for yourself, you can take a look at the solar activity map for 2024, for instance. This year saw a series of solar flares—outbursts of streams of high-energy particles—that resulted in some of the strongest geomagnetic storms in the last 20 years. Some of these storms were so powerful that they caused auroras at much lower latitudes than usual, both in the northern and southern hemispheres.

Scientists have long wondered whether the Sun could be an even more "frenzied" star, capable of producing much more powerful solar flares. To answer this question, researchers often look to the past, seeking evidence of the strongest solar "tantrums" in ancient glacial rocks as well as in the annual rings of trees.

However, these are indirect sources, and it is impossible to calculate the periodicity of super flares based on them. Ground-based measurements of solar radiation reaching Earth from our star have only become available since the beginning of the space age. This means that too little time has passed to gather statistics on super flares and use them to determine how frequently they occur.

Another way to learn about the anomalous behavior of our Sun is to study similar stars, which is exactly what an international team of astrophysicists led by Alexander Shapiro from the University of Graz (Austria) did.

Modern space telescopes simultaneously observe thousands of stars and record fluctuations in their brightness in visible light. Super flares, which release an amount of energy exceeding one octillion joules in a short span of time, appear in observational data as brief, pronounced spikes in brightness. While scientists cannot study the Sun over thousands of years, they can observe the behavior of thousands of solar-type stars over a shorter period, which helps estimate how often super flares occur.

Shapiro and his team analyzed data from 56,450 sun-like stars observed by NASA's Kepler space telescope from 2009 to 2013. As a result, the researchers obtained information covering 220,000 years of stellar activity.

In their work, the astrophysicists carefully selected stars, ensuring that the chosen celestial bodies were "relatives" of the Sun. Thus, they only considered objects whose brightness and surface temperature were close to solar values.

The researchers also excluded a number of potential errors—cosmic radiation, passing asteroids or comets, and stars that are not sun-like, which may have accidentally appeared near sun-like stars in the Kepler images. To address this, the team analyzed images of each potential super flare and included in the statistics only those events that could be attributed to one of the selected stars.

As a result, Shapiro's team identified 2,889 super flares for every 2,527 stars. This means that, on average, one sun-like star produces a super flare approximately once a century. In other words, such phenomena occur much more frequently than scientists previously thought. Other researchers had concluded that the average intervals between flares were one thousand or even ten thousand years. However, in their studies, scientists were unable to accurately determine the source of the recorded super flares.

The authors of the new study do not claim to have learned how to accurately predict the occurrence of super flares on the Sun, but they emphasized that engineers need to develop a series of measures in case such an event occurs, such as planning for the shutdown of satellites.

In 2031, the European Space Agency plans to launch the Vigil space station, which is intended to serve as a timely forecasting system for solar flares. The device will monitor solar activity around the clock and warn of dangerous phenomena that could affect the operation of ground systems and satellites in low Earth orbit.

It is worth noting that the strongest geomagnetic storm in recorded history, caused by a solar flare, occurred in 1859 (also known as the "Carrington Event"). At that time, telegraph systems across Europe and North America went down. Experts estimate that during the flare associated with this event, only one-hundredth of the energy released during a super flare was emitted. If the "Carrington Event" were to occur today, both surface infrastructure and satellites would be at risk.

For more detailed results from Shapiro's team's research, you can refer to the article published in the journal Science.