Imma Perfetto
Cosmos science journalist
Superflares are violent solar tantrums that release immense amounts of energy, more powerful than the largest solar flares observed from the Sun, within a very short period.
Scientists are trying to discover if our Sun can generate superflares and, if so, how often they might happen.
But interesting, and somewhat scary, newresearch, has now revealed that superflares occur roughly once per 100 years in other stars like our Sun elsewhere in the universe.
“We cannot observe the Sun over thousands of years,” says Sami Solanki, Director at the Max Planck Institute for Solar System Research and co-author of the new paper published in the journal Science.
“Instead, however, we can monitor the behaviour of thousands of stars very similar to the Sun over short periods of time. This helps us to estimate how frequently superflares occur.”
Solanki and collaborators analysed brightness measurements captured by the Kepler space telescope between 2009 and 2013. To be included in the study, stars had to have a similar surface temperature and brightness as the Sun.
“In their entirety, the Kepler data provide us with evidence of 220,000 years of stellar activity,” says co-author Alexander Shapiro from the University of Graz in Austria.
They identified 2,889 superflares on 2,527 Sun-like stars out of the 56,450 observed.
They found the stars produce superflares every hundred years or so, with energy described as “…an order of magnitude more energetic than any solar flare recorded during the space age.”
Solar flares are often, but not always, accompanied by coronal mass ejections (CMEs) which expel large volumes of plasma from the Sun. These accelerate charged particles to high energies, known as solar energetic particles (SEPs), which can produce radioactive isotopes when they reach Earth.
Radioactive carbon-14 isotopes deposited in natural archives, such as tree rings and glacial ice, have revealed 5 confirmed (and 3 candidate) extreme SEP events in the past 12,000 years. That’s one roughly every 1,500 years.
However, it is possible that more of these violent particle events and superflares occurred on the Sun in the past.
“It is unclear whether gigantic flares are always accompanied by coronal mass ejections and what is the relationship between superflares and extreme solar particle events,” says co-author Ilya Usoskin from the University of Oulu in Finland.
A superflare released today would prove disastrous to the infrastructure on the Earth, especially satellites. However, the researchers acknowledge that the flaring stars in the Kepler observations may not be representative of the Sun.
“We cannot exclude the possibility that there is an inherent difference between flaring and nonflaring stars that was not accounted for by our selection criteria,” they write.
