A powerful eruption on a nearby dwarf star has been detected, capable of stripping away the atmosphere of any Earth-like planets orbiting it. This finding, published in the journal Nature, is the first confirmed observation of a coronal mass ejection (CME) — an immense blast of plasma — originating from a star beyond our sun. Understanding these powerful stellar events is crucial for astronomers searching for habitable worlds.
The discovery was made by analyzing a “type II radio burst” emitted from StKM 1-1262, a star roughly 40 light-years away. These bursts occur when CMEs accelerate through the outer atmosphere of a star and into space, creating shock waves that generate radio waves detectable on Earth. Although similar events had been theorized before, this observation provides the most compelling evidence to date of an CME originating from another star.
StKM 1-1262 belongs to the M dwarf class – smaller, cooler, and more active than our sun. They are frequent flares and CMEs, making them prime targets for searching for exoplanets (planets outside our solar system). M dwarfs are especially attractive because planets around them tend to form closer to their stars, making them easier to detect.
However, this heightened activity presents a significant challenge. The “Goldilocks zone” – the region around a star where conditions might allow liquid water to exist on a planet’s surface – is much closer to an M dwarf than it is to our sun. This means any hypothetical Earth-like planets in this habitable zone would be subjected to far more frequent and intense CMEs.
“One of the problems could be that these CMEs happen so regularly, and they’re hitting the planets so regularly, that they strip the atmosphere,” explains Dr. Joe Callingham, lead study author and a radio astronomer at the Netherlands Institute for Radio Astronomy. “So, great – you’re in the Goldilocks zone, but you’ve got no help here because the stellar activity destroyed [the chances for life].”
The research team used the Low Frequency Array (LOFAR) telescope network in Europe to detect the initial radio burst. LOFAR is currently the most sensitive radio telescope ever built, and sophisticated data processing techniques were needed to pinpoint this faint signal. Subsequent observations with ESA’s XMM-Newton space telescope confirmed that StKM 1-1262 was indeed an M dwarf and provided crucial information about its rotation rate and brightness in X-rays. This allowed the team to calculate the speed of the CME, which was clocked at nearly 1,500 miles per second (2,400 kilometers per second).
This exceptional velocity coupled with the high density of the CME suggests that it would be capable of stripping away the atmospheres of any planets in close orbit around StKM 1-1262. While LOFAR has proven effective for this discovery, the team anticipates a future breakthrough with the Square Kilometer Array (SKA), an even larger radio telescope array currently under construction in Australia and South Africa. The SKA is expected to be operational in the 2030s and should dramatically increase our capability to detect extrasolar CMEs, enabling astronomers to map their frequency and characteristics across different types of stars.
Understanding the frequency and severity of these stellar outbursts will refine our understanding of planetary habitability around smaller, more common stars like M dwarfs.
