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The hunt for planets that could harbor life maybe just shrunk dramatically.
Scientists had long hoped and theorized that the most common type of star in our universe – called an M dwarf – might host nearby planets with potentially carbon-rich atmospheres perfect for creating life. But in a new study of a world orbiting an M dwarf 66 light-years from Earth, researchers found no indication that such a planet could retain an atmosphere.
Without a carbon-rich atmosphere, a planet is unlikely to be hospitable to living things. Carbon molecules are, after all, considered the building blocks of life. And the results don’t bode well for other types of planets orbiting M dwarfs, said study co-author Michelle Hill, a planetary scientist and doctoral student at the University of California, Riverside.
“The radiation pressure from the star is immense, enough to blow out a planet’s atmosphere,” Hill said in a post on the university’s website.
M dwarf stars are known to be volatile, spewing solar flares and raining radiation down on nearby celestial bodies.
But for years the hope had been that large enough planets orbiting near M dwarfs might find themselves in a Goldilocks environment, close enough to their little star to stay warm and big enough to cling to. its atmosphere.
The nearby M dwarf, however, may be too intense to keep the atmosphere intact, according to the new study, which has been published in The Astrophysical Journal Letters.
A similar phenomenon occurs in our solar system: the Earth’s atmosphere is also deteriorating due to the explosions of its nearby star, the sun. The difference is that Earth has enough volcanic activity and other gas-emitting activity to replace atmospheric loss and make it barely detectable, the research found.
However, the dwarf planet M examined in the study, GJ 1252b, “could have 700 times more carbon than Earth, and it still wouldn’t have an atmosphere. It would accumulate initially, then decrease and erode,” study co-author and UC Riverside astrophysicist Stephen Kane said in a press release.
GJ 1252b orbits less than a million kilometers from its home star, called GJ_1252. The planet reaches sweltering daytime temperatures of up to 2,242 degrees Fahrenheit (1,228 degrees Celsius), according to the study.
The existence of the planet was first suggested by NASA’s Transiting Exoplanet Survey Satellite (TESS) mission. Then astronomers ordered the nearly 17-year-old Spitzer Space Telescope to target the region in January 2020 — less than 10 days before Spitzer was disabled forever.
The investigation of whether GJ 1252b had an atmosphere was led by University of Kansas astronomer Ian Crossfield and involved a group of researchers from UC Riverside, NASA’s Jet Propulsion Laboratory, Caltech, from the University of Maryland, the Carnegie Institution for Science, the Max Planck Institute for Astronomy, McGill University, University of New Mexico and University of Montreal.
They pored over data produced by Spitzer, looking for emission signatures or signs that a gaseous bubble might envelop the planet. The telescope captured the planet as it passed behind its home star, allowing researchers to ‘watch starlight as it passes through the planet’s atmosphere’, giving a ‘spectral signature of the atmosphere’ — or lack thereof, Hill said.
Hill added that she was not shocked to find no sign of atmosphere, but was disappointed. It searches for moons and planets in “habitable zones,” and the results have made observing the worlds surrounding the ubiquitous M dwarf stars slightly less interesting.
Researchers hope to gain even more clarity on these types of planets with the help of the James Webb Space Telescope, the most powerful space telescope to date.
Webb will soon set his sights on the TRAPPIST-1 system, “which is also an M dwarf star with a bunch of rocky planets around it,” Hill noted.
“There is a lot of hope that it can tell us whether or not these planets have an atmosphere around them,” she added. “I guess M dwarf enthusiasts are probably holding their breath right now to see if we can tell if there’s an atmosphere around these planets.”
There are, however, still plenty of interesting places to hunt habitable worlds. In addition to looking at planets further away from M dwarfs that might be more likely to retain an atmosphere, there are still about 1,000 solar stars relatively close to Earth that might have their own planets spinning in habitable zones, according to the post. UC Riverside about the study.