Scientists: The Universe’s Most Common Stars Could Make Alien Life Impossible
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TAMPA (CBS Tampa) – The most common type of star in the universe may be a planet killer, reports Space.com.
NASA’s Kepler space observatory has revealed that at least half of these stars are orbited by rocky planets that are one-half to four times the mass of Earth.
Red dwarf stars are up to 50 times dimmer than our sun and are just 10 to 20 percent as massive. They make up to 70 percent of the stars in the universe.
And since they are relatively cold, the “goldilocks zone” where life could flourish is much closer to the star, even closer than Mercury is to the sun.
But this can create its own obstacles to the development of life, said lead study author Ofer Cohen, a space physicist at the Harvard-Smithsonian Center for Astrophysics.
“(W)hen you put a planet so close to its star, the space environment it will face is very extreme,” Cohen told Space.com. “The planet has to face the stellar wind of particles streaming from the red dwarfs.”
At such a close distance, the stellar wind would act like a sandblaster on the planet’s surface.
“Even though the planet is within the conventional definition of the habitable zone, it most likely does not have an atmosphere,” Cohen said. “Without an atmosphere, all water would be lost on the surface.”
And water, so far as we know, must be present for life to begin.
Cohen and his team created computer models for several different types of planets that might orbit close to a red dwarf. They found that even if planets had magnetic fields as strong as Earth’s, they would lose their atmospheres on the order of a couple of million years.
But not all hope is lost. Astronomers are now trying to find out if a planet might fare if it started with an atmosphere as thick as or thicker than Venus.
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