Dying Stars May Give Frozen Worlds a Second Chance at Life

Tuesday, 17 May 2016 - 1:27PM
Astrobiology
Alien Life
Tuesday, 17 May 2016 - 1:27PM
Dying Stars May Give Frozen Worlds a Second Chance at Life
When a normal yellow star, like our Sun, starts to reach the end of its life, it swells up to hundreds of times its normal size and becomes a extremely hot and bright red giant, engulfing any planet that gets too close. But according to new research from the Carl Sagan Institute at Cornell, this transformation could render any planet that escapes this fate more habitable, particularly the more distant, frozen worlds of our solar system.

When searching for Earth-like planets, astronomers focus on the "habitable zone," or the area around a star that is far enough away that liquid water won't evaporate but close enough that it won't freeze. In this new study, the Cornell researchers modeled the locations of habitable zones for older stars, and found that the habitable zone changes significantly at the end of a star's life.

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"When a star ages and brightens, the habitable zone moves outward and you're basically giving a second wind to a planetary system," said one of the team, Ramses M. Ramirez, in a statement.
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In our solar system, that means that frozen worlds that are known to house water ice, such as Europa and Enceladus, could become Earth-like planets that are veritable havens for alien life. Meanwhile, Mercury and Venus will be engulfed by the Sun, and Earth will become prohibitively hot, so the habitable zone is simply shifted further away from the dying star.

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"Long after our own plain yellow sun expands to become a red giant star and turns Earth into a sizzling hot wasteland, there are still regions in our solar system – and other solar systems as well – where life might thrive," said co-author Lisa Kaltenegger.
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This not only means that life could exist in our solar system long after Earth is gone, but could also change our methodology for searching for alien life. When searching for habitable exoplanets, astronomers often zero in on middle-aged stars, like our own Sun, with similar habitable zones. But according to this new research, we should be looking at stars at all different stages of life, particularly older stars, which have similarly wide habitable zones that are just more distant from the star.

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"In the far future, such worlds could become habitable around small red suns for billions of years, maybe even starting life, just like Earth," said Kaltenegger. "That makes me very optimistic for the chances for life in the long run."
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Space
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Alien Life

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