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Exoplanets: The search for habitable planets may just have narrowed

Exoplanets: The search for habitable planets may just have narrowed
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The hunt for planets that could harbor life can only have narrowed dramatically.

Scientists had long hoped and theorized that the most common type of star in our Universe – dubbed the M dwarf – could host nearby planets with atmospheres potentially rich in carbon and perfect for the creation of life. But in a new study of a world orbiting an M dwarf 66 light-years from Earth, researchers found no evidence such a planet could even hold an atmosphere.

Without a carbon-rich atmosphere, it is unlikely that a planet would be hospitable to living things. After all, carbon molecules are 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 graduate student at the University of California, Riverside.

“The star’s radiation pressure is immense, enough to blow away a planet’s atmosphere,” Hill said. in a post on the university’s website.

M dwarf stars are known for being volatile, emitting solar flares and raining down radiation on nearby celestial bodies.

But for years it had been hoped that fairly large planets orbiting near M dwarfs could be in a Goldilocks environment, close enough to their small star to stay warm and large enough to attach to its clinging atmosphere.

However, the nearby M dwarf may be too intense to keep the atmosphere intact, the researchers said new studypublished in The Astrophysical Journal Letters.

A similar phenomenon is happening in our solar system: the Earth’s atmosphere is also deteriorating due to outbursts from its nearby star, the Sun. The difference is that the Earth has enough volcanic activity and other gas-emitting activity to replace the atmospheric loss and make it almost undetectable, according to the research.

The M dwarf planet studied in the study GJ 1252b, “could have 700 times more carbon than Earth, and it still wouldn’t have an atmosphere. It would build up at first, but then die down and erode,” Stephen Kane, study co-author and UC Riverside astrophysicist, said in a press release.

GJ 1252b orbits less than a million miles from its host star named GJ_1252. The planet reaches hot daytime temperatures of up to 2,242 degrees Fahrenheit (1,228 degrees Celsius), according to the study.

The planet’s existence was first suggested by NASA’s Transiting Exoplanet Survey Satellite, or TESS, mission. Then astronomers ordered the nearly 17-year-old Spitzer Space Telescope to target the area in January 2020 — less than 10 days earlier Spitzer has been deactivated forever.

The investigation into whether GJ 1252b had an atmosphere was led by University of Kansas astronomer Ian Crossfield and included a group of researchers from UC Riverside, NASA’s Jet Propulsion Laboratory, Caltech, the University of Maryland, the Carnegie Institution for Science, the Max Planck Institute for Astronomy, McGill University, the University of New Mexico and the University of Montreal.

This illustration shows a possible scenario for the hot, rocky exoplanet called 55 Cancrie, which is nearly twice the width of Earth.  Data from NASA's Spitzer Space Telescope showed that the planet experiences extreme temperature fluctuations.

They pored over the data produced by Spitzer, looking for emission signatures or signs that a gas bubble might be enveloping the planet. The telescope caught the planet as it passed behind its host star, allowing researchers to “view starlight as it streams through the planet’s atmosphere” and gave a “spectral signature of the atmosphere” — or lack thereof, said Hill.

Hill added that she wasn’t shocked to find no signs of atmosphere, but was disappointed. It’s looking for moons and planets in “habitable zones,” and the results made it a little less interesting to look at worlds orbiting the ubiquitous M dwarf stars.

Researchers hope to gain even more clarity about these types of planets with the help of the James Webb Space Telescope, the most powerful space telescope to date.

Webb will soon turn his attention to those TRAPPIST-1 system“which is also an M dwarf star with a bunch of rocky planets around it,” noted Hill.

“There is great hope that it can tell us whether or not these planets have an atmosphere,” she added. “I think the M-dwarf enthusiasts are probably holding their breath right now to see if we can tell if there’s an atmosphere around these planets.”

However, there are still many interesting places to look for habitable worlds. Aside from looking for planets farther from M dwarfs that might be more likely to retain an atmosphere, there are still about 1,000 sun-like stars relatively close to Earth that might have their own planets orbiting in habitable zones, he said UC Riverside paper on the study.

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