The Japan Times - Astronomers spot storm on another star for first time

Solar storms on the Sun sometimes shoot out huge eruptions known as coronal mass ejections, which can disrupt satellites when they arrive at Earth -- and create colourful auroras that dance across the sky.

In fact, a particularly powerful solar storm caused auroras as far south as the US city of Tennessee on Wednesday, according to the National Oceanic and Atmospheric Administration.

Auroras were also visible in the skies above New Zealand, AFP images showed, with more expected into Wednesday night.

However, observing such a storm on a distant star had proven difficult for astronomers.

New research, published in the journal Nature on Wednesday, revealed that an international team of researchers has finally achieved the feat.

The discovery used data from a European network of telescopes called LOFAR.

The team of astronomers has been using LOFAR since 2016 to detect the most extreme and violent events in the universe -- such as black holes -- which emit relatively stable radio signals over time.

"We always have stars in the telescope's field of view but generally we're not interested in them," Cyril Tasse, a Paris Observatory astronomer and the study's co-author, told AFP.

However, the researchers have set up a data processing system that also records what is going on with the stars behind the behemoths they are chasing.

In 2022, the team decided to find out "what had been caught in this net", Tasse said.

They found that there was a huge explosion which only lasted a minute on May 16, 2016. It came from a red dwarf star called StKM 1-1262 more than 133 light years away.

The team then determined it was a coronal mass ejection -- a stellar storm.

"It's the first time we have detected one" on a star other than our own, Tasse said.

But this coronal mass ejection was "at least 10,000 times more violent than known solar storms" on the Sun, he added.

- Atmosphere killers -

The discovery could have an impact on the search for planets beyond our solar system that have the potential to host life.

Red dwarfs, which have a mass of between 10 and 50 percent that of our Sun, have proven to be the most likely stars in the universe to host planets that are roughly the size of Earth.

"The first radio detection inaugurates a new era for space weather applied to other star systems," said Philippe Zarka, research director at the Paris Observatory and a study co-author.

"This emerging field opens up major perspectives for how the magnetic activity of stars influence the habitability of the planets that surround them."

Tasse said that it appears that red dwarf stars have "much more erratic and violent" behaviour than the Sun.

"The implication is that these stars can be rather inhospitable when it comes to life and exoplanets," because they have storms so powerful they could destroy the atmospheres of planets nearby, he added.

H.Takahashi--JT