Are superflares formed by the same mechanism as solar flares? And could our own Sun be capable of producing a superflare? The answers might alarm you.
By Lola Gayle, Editor-at-large
Earth is often bombarded by energetic particles from solar eruptions. When those particles interact with Earth’s magnetic field they cause beautiful aurora, but when the Sun unleashes a larger solar eruption, it could have truly severe consequences on Earth. Still, these eruptions from our unpredictable neighbor are nothing compared to the ‘superflares‘ we see around other stars in the Universe.
The Kepler mission first spotted superflares four years ago, but they do they have anything in common with those from our own Sun? Are they formed by the same mechanism as solar flares? And, if so, does that mean that the Sun is also capable of producing a superflare?
In 2016, an international research team led by Christoffer Karoff from Aarhus University, Denmark, was able to provide alarming new answers to some of these questions which they published in the journal Nature Communications.
When the Sun unleashes a monstrous flare, it can impact radio communication and power supplies on Earth. The largest eruption observed to date occurred on September 1, 1859. During that eruption, astronomers observed how one of the dark spots on the surface of the Sun suddenly lit up and shone brilliantly over the solar surface. This phenomenon had never been observed before and nobody knew what was to come, according to an Aarhus University statement.
On the morning of September 2, the first particles from that enormous eruption, known as the “Carrington Event,” reached the Earth. During that time, auroras could be seen as far south as Cuba and Hawaii, telegraph systems across the globe went haywire, and ice core records from Greenland indicate that the Earth’s protective ozone layer was damaged by the energetic particles from the solar storm.
The cosmos, however, contains other stars and some of these regularly experience eruptions that can be up to 10,000 times larger than the Carrington Event.
Solar flares occur when large magnetic fields on the Sun collapse and huge amounts of magnetic energy are released. Christoffer Karoff and his team have use observations of magnetic fields on the surface of almost 100,000 stars made with the new Guo Shou Jing telescope in China to show that these superflares are likely formed via the same mechanism as solar flares.
“The magnetic fields on the surface of stars with superflares are generally stronger than the magnetic fields on the surface of the Sun. This is exactly what we would expect, if superflares are formed in the same way as solar flares” Karoff explained.
Based on this evidence, it would seem that the Sun is not capable of creating a superflare because its magnetic field is too weak. However…
Out of all the stars with superflares the researchers analyzed, around 10 percent had a magnetic field with a strength similar to or weaker than the Sun’s magnetic field. Therefore, even though it is not very likely, it is not entirely impossible that the Sun could produce a superflare.
“We certainly did not expect to find superflare stars with magnetic fields as week as the magnetic fields on the Sun. This opens the possibility that the Sun could generate a superflare – a very frightening thought” Karoff said.
In the event the Sun did unleash a superflare directed at Earth, it would have significant consequences. As expected, electronic equipment would be severely impacted, but that wouldn’t matter because we would probably all be dead since a superflare would devastate our atmosphere, disrupting the planet’s ability to support life.
Through their research, the team did find evidence for a small superflare that may have occurred in AD 775. Evidence of this was found in tree rings that show anomalously large amounts of the radioactive isotope 14C were formed in the Earth’s atmosphere. 14C is formed when cosmic-ray particles from the Milky Way, or especially energetic protons from the Sun, formed in connection with large solar eruptions, enter the Earth’s atmosphere.
The studies from the Guo Shou Jing telescope support the notion that the event in AD 775 was indeed a small superflare, i.e. a solar eruption 10-100 times larger than the largest solar eruption observed during the space age.
“One of the strengths of our study is that we can show how astronomical observations of superflares agree with Earth-based studies of radioactive isotopes in tree rings,” Karoff said.
By using observations from the Guo Shou Jing telescope, the researchers were able to evaluate how often a star with a magnetic field similar to the Sun would experience a superflare. The new study shows that the Sun, statistically speaking, should experience a small superflare every millennium. This is in agreement with idea that the event in AD 775 and a similar event in AD 993 were indeed caused by small superflares on the Sun.
Top Image: On August 31, 2012, a long prominence/filament of solar material that had been hovering in the Sun’s atmosphere, the corona, erupted out into space. Seen here from the Solar Dynamics Observatory, the flare caused an aurora on Earth on September 3. NASA/GSFC/SDO. Click here to view an image showing the size of this CME compared to the size of Earth.
DISCLAIMER: This is a repost of a previous article I wrote during my time trying to get a friend’s site off the ground. After two years and virtually no headway or money — and no promise of how long the site will remain online — I am forced to take back ownership of my content. Portions of the content have been updated.