Billions of Habitable Worlds in the Milky Way from ESO’s HARPS spectrograph

A new study from the European Southern Observatory announced via its HARPS planet finder, suggesting that Earth-sized rocky planets, are very common around faint red stars.

Red dwarfs – stars that are smaller and cooler than our sun – are extremely common, making up 80 percent of stars in the galaxy.



ESO’s HARPS spectrograph now estimates that there are billions of such planets in the Milky Way galaxy.

About one hundred of them in exists in less than 30 light years away.

Our new observations with HARPS mean that about 40% of all red dwarf stars have a super-Earth orbiting in the habitable zone where liquid water can exist on the surface of the planet,” says Xavier Bonfils (IPAG, Observatoire des Sciences de l’Univers de Grenoble, France), the leader of the team. “Because red dwarfs are so common — there are about 160 billion of them in the Milky Way — this leads us to the astonishing result that there are tens of billions of these planets in our galaxy alone.

“The habitable zone around a red dwarf, where the temperature is suitable for liquid water to exist on the surface, is much closer to the star than the Earth is to the Sun,” says Stéphane Udry (Geneva Observatory and member of the team). “But red dwarfs are known to be subject to stellar eruptions or flares, which may bathe the planet in X-rays or ultraviolet radiation, and which may make life there less likely.”



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