If superflares are comparable to celestial temper tantrums, our sun could get angry more often than previously thought, a researcher says report in the diary Science. A superflare, defined as a solar storm that releases over an octillion joules of energy in a short period of time, manifests itself in the data as a short, pronounced peak in brightness.
It can be helpful to understand the regularity of superflares, as they can be potentially harmful. For example, a violent solar storm in 1859 paralyzed the telegraph network in parts of Europe and North America. Although this Carrington event was one of the strongest solar storms in the last 200 years, it released only one hundredth of the energy of a superflare.
If these events occur hundreds of years apart, how can scientists measure their frequency?
“We cannot observe the sun for thousands of years,” says Sami Solanki, an astronomer at the Max Planck Institute for Solar System Research (MPS) and co-author of the paper said in a press release. “However, we can observe the behavior of thousands of Sun-like stars over short periods of time. This helps us estimate how frequently superflares occur.”
Learn more about solar storms
The team monitored data from NASA Kepler space telescope from 2009 to 2013, which included 56,450 Sun-like stars – meaning they only examined stars whose surface temperatures and brightness were similar to the Sun.
They also ruled out potential sources of error such as cosmic rays, passing asteroids or comets. The team discovered 2,889 superflares on 2,527 stars – an average of one superflare per century.
“We were very surprised that Sun-like stars are prone to such frequent superflares,” MPS co-author Valeriy Vasilyev said in a press release.
Previous studies by other groups found that superflares occurred every 1,000 – or even every 10,000 – years. However, these studies examined a more limited number of stars.
Read more: Our sun is capable of producing dangerous “superflares,” a new study says
Fewer solar storms on Earth?
However, physical evidence of superflare impacts on Earth suggests larger gaps than the average calculated in this study. Violent solar storms that hit Earth leave traces of various radioactive atoms. These atoms are archived in tree rings and glacial ice. Scientists can detect these atoms even thousands of years after their influx.
Using this method, researchers have identified five extreme solar particle events and three candidates over the past 12,000 years – an average of once every 1,500 years, with the most intense occurring in 775 AD.
However, it is possible that not all superflares emit the same types and amounts of radioactive particles. If this is the case, the number of events impacting Earth could be underestimated. And regardless of frequency, superflares are difficult to predict. New space-based instruments are being developed to predict these solar storms.
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Before joining Discover Magazine, Paul Smaglik worked as a science journalist for over 20 years, specializing in U.S. life science policy and global science career issues. He started his career in newspapers but moved to academic journals. His work has appeared in publications such as Science News, Science, Nature and Scientific American.