Solar storms can trigger auroras on Earth. This star’s explosion could destroy a planet’s atmosphere

For the first time, astronomers say they have spotted a giant explosion released by a star beyond our solar system. The eruption was similar in some ways to those unleashed by our sun, such as the solar storms that graced the night skies with auroras last week on Earth, but at a much grander — and ominous — scale.

Rather than triggering colorful northern lights, this powerful explosion was more likely to have potentially devastating consequences for any nearby planet, according to new research.

A coronal mass ejection, or a CME, was the likely cause of the explosive event. In our solar system, this phenomenon is a large cloud of ionized gas, called plasma, and magnetic fields that erupts from the sun’s outer atmosphere.

When such outbursts are large enough to reach Earth, they can cause space weather, or major disturbances of our planet’s magnetic field.
These powerful solar storms create auroras at Earth’s poles but can also disrupt communications, the power grid and satellite operations.

Astronomers have never been able to detect a coronal mass ejection releasing from another star — until now. Researchers described the groundbreaking finding in a study published Wednesday in the journal Nature.

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The star, named StKM 1-1262, is a red dwarf star about 130 light-years from Earth.

The stellar storm launched at a blazing 5.3 million miles per hour (2,400 kilometers per second). Such speed has only been clocked in about 1 in every 2,000 coronal mass ejections released from our sun, according to the study authors.

“The star behaves like an extremely magnetized, boiling bucket of plasma. This burst is 10 to 100 thousand times more powerful than the strongest the sun can produce,” study coauthor Cyril Tasse, research associate at the Paris Observatory, said via email. “This opens a window of extrasolar space weather.”

The dense, rapid burst of material hurled from the star was powerful enough that it could strip away the atmosphere of a closely orbiting planet.

Understanding how the violent activity of stars affects exoplanets is crucial as astronomers seek to determine whether any planet beyond our solar system is potentially habitable for life.

Seeking stellar explosions

Once released into space by a star, coronal mass ejections create a burst of radio waves while passing through the outer stellar atmosphere, called the corona.

“They are strong gusts of stellar wind that move faster than the speed of sound in the surrounding interplanetary space, creating a shock wave that is comparable to the sonic boom of a fighter jet,” said Mark Miesch, a research scientist at the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center. Miesch did not participate in the study.

Researchers spotted the radio signal while using new analytic software to sift through a survey of the sky that was conducted by the Low Frequency Array radio telescope, or LOFAR, nearly 10 years ago. LOFAR is composed of thousands of antennae in the Netherlands and across Europe to create one large radio telescope.

“This kind of radio signal just wouldn’t exist unless material had completely left the star’s bubble of powerful magnetism,” said lead study author Dr. Joe Callingham, associate professor at the University of Amsterdam’s Anton Pannekoek Institute for Astronomy. “In other words, it’s caused by a CME.”

Tasse and study coauthor Philippe Zarka, a senior researcher at the Paris Observatory, developed the new analysis technique, called Radio Interferometric Multiplexed Spectroscopy, or RIMS. It was based on wavelengths of light captured from thousands of stars to monitor them and determine how they changed over time, Tasse said.

“The idea was to try to detect radio signals from stars and exoplanets,” Tasse said. “This is an ideal technique for CMEs that evolve on timescales of minutes so you need continuous, high-time-resolution monitoring.”

The signal detected by RIMS was a type II radio burst, suggesting hot gas was sweeping away from the star into space. Unlike fast radio bursts, which are millisecond-long flashes of light with dubious origins, a type II radio burst occurs over minutes, Callingham said.

“The sweep encodes the density of material as the CME travels outwards,” Callingham said. “So not only from the radio burst can we tell mass has been lost from the star, we can also determine physical parameters like density.”

The team used data from the European Space Agency’s XMM-Newton mission, launched in 1999, to measure the star’s temperature, rotation and brightness through X-rays.

“We needed the sensitivity and frequency of LOFAR to detect the radio waves,” said study coauthor David Konijn, a doctoral student at the Netherlands Institute for Radio Astronomy, in a statement. “And without XMM-Newton, we wouldn’t have been able to determine the CME’s motion or put it in a solar context, both crucial for proving what we’d found. Neither telescope alone would have been enough — we needed both.”

Spotting coronal mass ejections releasing from other stars has proven difficult because they’re just too far away to observe the phenomenon directly, Callingham said. While previous hints of coronal mass ejections from other stars have surfaced, they could often be explained by other activity such as strong flares, and there were no definitive detections, Tasse added.

“Previous evidence for CMEs in other stars has mainly been concerned with the early stages of the event, when the plasma first lifts off from the star,” Miesch said.

But using a sensitive telescope like LOFAR and searching for the telltale radio signal enabled a direct discovery, Callingham said.

Miesch said the emission signature matches the known signatures of type II radio bursts from solar CMEs.

The clear detection of a type II stellar radio burst has long been sought after as an indicator of coronal mass ejections from other stars, said Kevin France, associate professor and astrophysicist at the University of Colorado Boulder. France has studied coronal mass ejections but did not participate in this research.

“This detection provides what is likely the strongest evidence yet that this phenomenon occurs beyond the solar system,” he wrote in an email. “This observation, and hopefully more like it, will allow us to better understand the violent early lives of these low mass stars that make up over 70% of all the stars in our Milky Way.”

The search for life

Red dwarf stars can have magnetic fields that are more than 1,000 times stronger than that of our sun, Callingham said.

StKM 1-1262 has half the mass of our star, but it rotates 20 times faster and boasts a magnetic field that is estimated to be 300 times more powerful, according to the study.

Scientists often find exoplanets orbiting these stars that are much fainter, cooler and smaller than our sun, and at a closer distance than planets in our solar system — sometimes completing one orbit in a matter of days.

Because red dwarf stars are less luminous and cooler than our star, the habitable zone — the distance from a star where conditions on the planet are warm enough to potentially support liquid water on its surface — is much smaller, meaning planets are more tightly clustered around the diminutive stars.

But astronomers have long questioned whether flares released from red dwarf stars could lash planets with harmful radiation. If a planet does have liquid water on its surface, which means it could potentially be habitable for life, then it also has a protective atmosphere.

Currently, it isn’t known whether any planets orbit StKM 1-1262, but based on previous research, almost every red dwarf star seems to host at least one planet, Callingham said.

“The protective magnetic field we have on Earth would not be able to withstand the pressure of the CME, exposing its atmosphere directly to CME (causing it to be stripped),” Callingham wrote in an email. “So even if the planet is in the perfect region around the star, its atmosphere would be lost quickly, leaving a barren rock behind (kind of like Mars).”

Next, the researchers want to try and determine how such small stars build and release such enormous energy, Tasse said — and figure out what impact repeated coronal mass ejections could have on nearby planets.

Callingham is also the head of the Square Kilometre Array Science Group at the Netherlands Institute for Radio Astronomy.

The Square Kilometre Array, expected to be completed in 2028, will include thousands of dishes and up to 1 million low-frequency antennae to create the world’s largest radio telescope, which could search for coronal mass ejections releasing from other stars.

“This is only the beginning, and hopefully a taste of what’s to come,” Miesch said. “Hopefully this will inspire follow-up studies to verify this is what we think it is and to further characterize how frequent such events are.”

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