Scientists warn 'superflares' could pose threat to Earth

Rodiano Bonacci
Giugno 12, 2019

It's the coolest and smallest star that scientists have observed emitting a rare white-light superflare - a sudden eruption of magnetic energy that unleashes huge quantities of radiation, according to a statement from the University of Warwick in the United Kingdom.

Very young stars tend to have more hostile personalities, and superflares are incredibly common in systems with stars that aren't as mature as our sun.

It was the year 2000 and scientists had never seen anything like it: astronomers reported evidence of "superflares" on distant stars - solar outbursts many thousands of times more energetic than typical solar flares.

If the sun produced a superflare today, the star would emit vast amounts of high energy radiation which could wreak havoc with electronics across our planet.

"Our study shows that superflares are rare events", Yuta Notsu, a researcher in Colorado University-Boulder's Laboratory for Atmospheric and Space Physics, said in a statement.

The dire study was published last May in the journal The Astrophysical Journal.

'For the Sun, it's once every few thousand years on average'. But a new research paper warns that a massive "superflare" could be inevitable, and if it hits Earth we might be in serious trouble. Perhaps our much older, quieter Sun would never do such a violent thing, we speculated.

And we could be overdue. "But there is some possibility that we could experience such an event in the next 100 years or so".

To investigate, Dr Notsu and his colleagues from Japan, the U.S. and the Netherlands studied superflares detected from 43 Sun-like stars using data from the European Space Agency's Gaia spacecraft and New Mexico's Apache Point Observatory. Working from a sample of about 90,000 Sun-like stars, the researchers identified more than 1,000 superflares from about 300 stars. They then used various star survey facilities, such as the Next Generation Transit Survey (NGTS) at the European Southern Observatory's Paranal Observatory, to record the brightness of the star over 146 nights.

An artist's depiction of a superflare on an alien star.

The age of a star is crucial in determining the frequency of a star's superflares.

And that raised an obvious question: Could a superflare also occur on our own sun?

NASA captured a solar flare April 17, 2016, in 4K quality. But it also found something odd about those stars themselves.

Dr Notsu said: "When our Sun was young, it was very active because it rotated very fast and probably generated more powerful flares". "The fact that we've observed this incredibly low mass star, where the chromosphere should be nearly at its weakest, but we have a white-light flare occurring shows that strong magnetic activity can still persist down to this level". In September 1859, a solar flare sent a wave of charged particles washing over our planet. In the intense geomagnetic storm that followed, which is now known as the Carrington Event, telegraph systems across the globe malfunctioned and sparked, and auroras were visible as far south as Cuba and Hawaii.

"If a superflare occurred 1,000 years ago, it was probably no big problem".

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