A powerful explosion discovered from a dwarf star was strong enough to blow away the atmosphere of an Earth-like planet that may have been lurking nearby, a new study suggests.
The study, published in the journal Nature on Wednesday (12 November), is the first to confirm a coronal mass ejection (CME), a large, high-speed burst of plasma from a star other than the Sun. As scientists search for habitable worlds, understanding how strong and frequent stellar eruptions occur is essential to deciding where to center their search, the study authors argue.
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The star, called StKM 1-1262, is an M dwarf. Statistically, M dwarfs are smaller and much more active than the Sun, so they emit more solar flares and CMEs. Nevertheless, M dwarfs are common in our universe, making them popular targets for life searches. Finding planets around these stars is also easy. Because M dwarfs are so small, planets tend to form much closer together (and therefore easier to detect) than planets around large stars similar to the Sun.
However, there are some caveats. Earth 2.0 is likely to be exposed to more CMEs than we experience on the Sun because M dwarfs are more active and the “Goldilocks zone” where water could exist on the surface of a theoretical rocky planet is closer to a faint star than Earth is to the Sun.
“One possible problem is that [that] “These CMEs occur very regularly, and they’re hitting the planets so regularly that they’re destroying the atmosphere,” Joe Cullingham, lead author of the study and a radio astronomer at the Netherlands Institute for Radio Astronomy, told Live Science in an interview. [the chances for life]”
a storm that tears the atmosphere
The researchers discovered the first burst of radio waves using the Low Frequency Array (LOFAR) radio telescope, a European antenna network primarily located in the Netherlands, and with the help of new data processing techniques from co-authors at the Paris Observatory. LOFAR is the most sensitive radio telescope ever built, Cullingham said, adding that thanks to algorithms researchers were “lucky” to find small bursts of light in the sky.
Follow-up observations by the European Space Agency’s XMM Newton Space Telescope showed the star’s temperature, along with its rotation (20 times faster than the Sun) and its brightness in X-rays, confirming that it is an M dwarf.
The rotation and brightness revealed the CME’s movement, and it was traveling at nearly 1,500 miles per second (2,400 kilometers per second). This speed is found in only 5% of similar outbursts on the Sun. The combined telescope observations also show that CMEs are moving with sufficient speed and density to blow away the atmospheres of planets in close orbits to their stars.
LOFAR is powerful, but the challenge is that this observation (combined with new data processing techniques) approaches the limits of the telescope’s resolution, Cullingham said. To observe more extrasolar CMEs, the research team is looking forward to scientific operations of the Square Kilometer Array, a giant radio telescope project under construction in Australia and South Africa, in the 2030s.
Collingham said the Square Kilometer Array should be able to discover “dozens to hundreds” of extrasolar CMEs within the first year, which will allow the team to better chart how often atmospheric stripping strikes occur and how CMEs vary by star type.
“This is very impactful, because as astronomers we are trying to find habitable planets. … That’s one of the key goals of astronomy over the next decade. I hope so. But it will probably take a lot longer, or maybe the rest of my life, to find Earth 2.0.”
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