A red dwarf 130 light-years away has just rewritten the rules of space weather. For the first time, astronomers have captured definitive evidence of a massive coronal mass ejection from a star other than the Sun-an eruption so fast and dense it could strip the atmosphere from any nearby planet in minutes.
The breakthrough came from a combination of the Low Frequency Array (LOFAR) radio telescope and the European Space Agency’s XMM-Newton space observatory. LOFAR’s network of more than 20,000 antennas revealed a short, intense type II radio burst-an unmistakable signature of a CME’s shock wave tearing through a star’s corona. “This kind of radio signal just wouldn’t exist unless material had completely left the star’s bubble of powerful magnetism,” said Joe Callingham of the Netherlands Institute for Radio Astronomy. XMM-Newton X-ray measurements confirmed the star’s identity as StKM 1-1262, a small, cool M-dwarf whose magnetic field is 300 times stronger than the Sun’s.
The eruption’s speed 2,400 km per second puts it among the fastest one in every 2,000 solar CMEs. Traveling at that speed, the blast would compress a planet’s magnetosphere to its surface, exposing it to sterilizing particle radiation. Julián Alvarado-Gómez of the Leibniz Institute for Astrophysics Potsdam, not involved with the study, said, “Sometimes you only need one of these big guys to come your way.” The luminosity of the CME was about 100 times greater than anything seen from the Sun, rivaling the infamous 1859 Carrington Event, which disrupted telegraph systems worldwide and lit auroras as far south as Central America.
Given that planets around M-dwarfs are among the prime targets in the search for habitable worlds, this detection is certainly a sobering reminder of the hazards posed by stellar activity. Though they are small and dim, their intense magnetic fields drive frequent flares and, now confirmed, powerful CMEs. In fact, such eruptions have been shown to erode atmospheres over millions of years when combined with high stellar wind pressure. Planets in the “Goldilocks zone” might become barren without a strong magnetic shield like Earth’s.
The challenge of detecting CMEs beyond the Sun has persisted for decades. In fact, the Sun’s CMEs are imaged routinely with coronagraphs, but the same method is orders of magnitude harder for distant stars. Instead, astronomers have harnessed indirect signatures such as type II radio bursts and EUV coronal dimming. For CME-induced dimming, the plasma ejection reduces the intensity of extreme-ultraviolet emission lines emanating from across the corona, with the depth of dimming scaling with CME mass and the rate of dimming with CME speed. Instruments such as the proposed ESCAPE mission could make routine detections possible, enabling statistical studies of CME frequency across stellar types, with an effective area up to 100 cm² and sub-2 Å spectral resolution.
The implications for the habitability of exoplanets are profound. Research led by Chuanfei Dong at the Princeton Plasma Physics Laboratory modeled how stellar wind and CME bombardment can strip atmospheres from planets around red dwarfs-even ones originally flush with water. The process accelerates on tidally locked worlds, where one hemisphere constantly faces the onslaught. For water worlds, ancient stellar storms could dry their oceans long before life has a chance to evolve.
Historical analogs add weight to the concern. Observations of young Sun-like stars such as EK Draconis reveal multi-temperature CMEs, which are ejecting plasma at hundreds of kilometers per second, producing shocks and energetic particles capable of reshaping planetary atmospheres. In the youth of our own solar system, such events may have influenced the emergence of life on Earth while stripping Mars and Venus of their early atmospheres. For StKM 1-1262, the team estimates such eruptions may occur once every 500 years. Rare on human timescales, they are frequent enough in geological terms to pose a persistent threat to planetary habitability.
As NASA’s James Webb Space Telescope continues its search for atmospheres around rocky M-dwarf planets-with early results showing many have already lost theirs-this first confirmed stellar CME offers a crucial piece of the puzzle. Future arrays like the Square Kilometer Array will extend these detections, building a statistical map of stellar space weather. As Callingham said, “If you want to find an Earth-like planet somewhere else, we’ve got to know how often these things happen.” The answer may determine whether alien worlds can keep their skies or lose them to the fury of their stars.
