According to a new study, a tremendous blast observed from a dwarf star was strong enough to remove the atmosphere of any nearby planets that might have resembled Earth. The study published in Nature on November 12 marks the first confirmation of a coronal mass ejection (CME) from a star other than the Sun.
A type II radio burst, caused by the shock wave of a CME as it escapes a star’s atmosphere into interplanetary space, was detected from a star located 40 lightyears away, significantly farther than Alpha Centauri. This finding is particularly noteworthy as it represents the first conclusive detection of a type II radio burst from an extrasolar star, providing strong evidence for the existence of CMEs beyond our solar system.
The star StKM 1-1262 is categorised as an M dwarf, a type of star that is typically smaller and significantly more active than the Sun. M dwarfs frequently emit coronal mass ejections (CMEs) and solar flares, making them key targets for searches for extraterrestrial life.
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Their smaller size results in planets forming at closer orbits, facilitating their detection compared to planets around larger, sun-like stars. However, this proximity comes with challenges due to the heightened stellar activity associated with M dwarfs. The “Goldilocks zone,” where conditions could support liquid water on a rocky planet, is situated closer to these stars.
Consequently, potential Earth-like planets would be more susceptible to the frequent and intense CMEs, which could erode their atmospheres and diminish the life chances. Joe Callingham, a lead researcher at the Netherlands Institute for Radio Astronomy, highlights that while these planets may lie within the habitable zone, the destructive effect of ongoing stellar activity poses significant obstacles to sustaining life.
An atmosphere-shredding storm
The detection of an initial burst of radio waves was achieved using the Low Frequency Array (LOFAR) radio telescope, part of a European network primarily situated in the Netherlands. This telescope’s sensitivity, along with data processing support from the Paris Observatory, allowed researchers to identify a small light burst in the sky.
Subsequent observations using the European Space Agency’s XMM-Newton space telescope confirmed the nature of this object as an M dwarf star. Notably, this star rotates at a speed 20 times that of the sun and exhibits significant X-ray brightness.
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The investigation unveiled that the coronal mass ejection (CME) associated with this M dwarf star travels at an impressive speed of nearly 1,500 miles per second (2,400 kilometres per second), which is a velocity characteristic of only 5% of similar solar events. Additionally, the CME is sufficiently fast and dense to potentially strip away the atmospheres of any proximal planets, bringing into question their habitability.
The findings also indicated that the team is approaching the resolution limits of LOFAR, which has spurred anticipation for the forthcoming Square Kilometre Array (SKA). This ambitious radio telescope project, scheduled to begin scientific operations in Australia and South Africa in the 2030s, is projected to enhance detection capabilities significantly.
Callingham, a member of the research team, conveyed optimism about the SKA’s potential to detect “tens to hundreds” of extrasolar CMEs in its inaugural year. This advancement would enable a more thorough understanding of the frequency and variety of atmospheric-stripping events across different types of stars.
Ultimately, the research aims to assist astronomers in their pursuit of identifying habitable planets, which Callingham considers one of the key objectives in astronomy for the next decade. Nonetheless, he acknowledges that the search for an Earth-like exoplanet, often dubbed “Earth 2.0,” could be a lengthy endeavour.
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