Hubble finds evidence of water on Trappist-1 planets

Three of the five potentially wet planets lie within the so-called habitable zone where the temperature allows water to exist in liquid form.
By Jackie Flores | Sep 04, 2017
Earlier this year, astronomers announced the discovery of seven Earth-sized planets orbiting an ultra cool dwarf star, dubbed TRAPPIST-1, located only 40 light-years away.

Now, in an attempt to discover out if water is likely to exist on these planets, an international team of astronomers using the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope has found that the five outermost planets could have large bodies of water on their surfaces.

Three of the five potentially wet planets lie within the so-called habitable zone where the temperature allows water to exist in liquid form.

The team of scientists, led by the Swiss astronomer Vincent Bourrier from the Observatoire de l'Universit de Genve, used the STIS to calculate the amount of ultraviolet radiation received by the TRAPPIST-1 planets.

"Ultraviolet radiation is an important factor in the atmospheric evolution of planets," explained Bourrier in a statement. "As in our own atmosphere, where ultraviolet sunlight breaks molecules apart, ultraviolet starlight can break water vapor in the atmospheres of exoplanets into hydrogen and oxygen."

Bourrier's team calculates that the two innermost planets, TRAPPIST-1b and TRAPPIST-1-c, which absorb the most ultraviolet light, have lost large amounts of water over the past 8 billion years. But for the five outer planets, the loss has been considerably less.

"While our results suggest that the outer planets are the best candidates to search for water with the upcoming James Webb Space Telescope," added Bourrier, "they also highlight the need for theoretical studies and complementary observations at all wavelengths to determine the nature of the TRAPPIST-1 planets and their potential habitability."

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