March 24, 2016

What is a superflare? Could our sun produce one?

Solar flares, sudden flashes of brightness produced by stars like our sun, are made up of highly energetic particles that often come into contact with the Earth’s magnetic field, producing auroras in our planet’s atmosphere. But what would happen if they were far more powerful?

In a new study published Thursday in the journal Nature Communication, Christoffer Karoff of Aarhus University in Denmark and an international team of colleagues investigated what would happen if the sun ever produced a superflare – strong explosions with energy levels thousands of times higher than traditional solar flares – and whether it could actually happen.

First discovered by the Kepler mission four years ago, superflares have been mysterious, which has left scientists to ponder whether or not they are produced through the same mechanisms as a normal solar flare. To investigate the issue, they conducted a series of observations with China’s Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST).

Karoff and his colleagues studied 5,648 solar-like stars, including 48 superflare stars, and found that while most of these highly energetic events took place on stars characterzed by much larger chromospheric emissions than the sun, some had activity levels that were comparable to or even less than the sun, suggesting that solar flares and superflares may share a common origin.

Not only could a superflare hit Earth; evidence suggests one already has

Historically speaking, the sun has produced some solar flares and coronal emissions which have played havoc on Earth-based radio communication and power sources. The largest eruption of its kind occurred in September 1859, when one of the sun’s dark spots suddenly lit up and caused a solar storm that interfered with telegraphs and was felt as far south as Cuba and Hawaii.

In a more technologically-dependant age, this storm (also known as the Carrington Event) could cause widespread issues, but even it pales in comparison to the eruptions that regularly take place on some of the other stars in the cosmos, the researchers said in a statement. In fact, some events can be up to 10,000 times more powerful than the Carrington Event, they noted.

Could a superflare ever be produced by the sun? Based on Karoff’s teams findings, it seems an unlikely possibility, as the sun’s magnetic field is too weak. However, in light of the fact that 10 percent of the stars they analyzed had magnetic fields that were either as strong or even slightly weaker than the sun’s, the authors say that it would not be impossible our host star to produce a superflare – which Karoff called “a very frightening thought.”

Were such a massive, highly energetic solar eruption to impact the Earth today, the researchers warn that it would have devastating consequences, not just for our technology but for the planet’s atmosphere and its very capacity to support living creatures. Furthermore, they said, the presence of the radioactive isotope Carbon-14 in tree rings appears to indicate that the sun might have already produced a tiny superflare during the year 775 AD – a claim observations made with the LAMOST telescope seem to support, the researchers noted.


Image credit: NASA