Hydrogen and helium atmospheres could keep exoplanets warm enough to be habitable for billions of years, even at huge distances from their stars.
Astrobiologists normally think of the habitable zone as the comfortable region of space relatively close to a star (but not too close). Life needs water — liquid, not ice — and the distant reaches of a star system should be too cold for liquid water to exist. That idea guides where astronomers search for exoplanets and where the Webb telescope and others will search for chemical evidence of life in alien atmospheres. But a new study suggests we should give more distant orbits a second look.
In a study published Monday in the journal Nature Astronomy, University of Zurich planetary scientist Marit Mol Lous and her colleagues say that an unusual type of exoplanet could keep itself warm — and potentially habitable — for several billion years at roughly the equivalent of Saturn’s distance from the Sun.
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