Water could be present on some of the Earth-sized planets orbiting the dwarf star TRAPPIST-1, according to work from an international group of astronomers. They utilized the NASA/ESA Hubble Space Telescope to estimate substantial amounts of water could be present in the outer planets, including three in the habitable zone. This boosts the possibility those planets are livable.
Astronomer Vincent Bourrier of the Observatoire de l’Université de Genève led an international team that included scientists from NASA and MIT to attempt to determine if there’s water 40 light-years away on the seven Earth-sized planets orbiting TRAPPIST-1, a system which claims the biggest number of Earth-sized planets we’ve found to date. These researchers used the Space Telescope Imaging Spectograph on Hubble to scrutinize how much ultraviolet radiation the TRAPPIST-1 planets receive.
Bourrier said ultraviolet starlight can break water vapor into oxygen and hydrogen. And those elements can escape as ultraviolet rays with more energy to heat a planet’s upper atmosphere. It’s possible for Hubble to detect escaped hydrogen gas, which can act as a “possible indicator of atmospheric water vapor,” according to the statement on the research.
Some of the outer planets, including e, f, and g, could have water on their surfaces. During the last eight billion years, the inner planets of the TRAPPIST-1 system “could have lost more than 20 Earth-oceans-worth of water,” according to the statement. But the outer planets might have not lost that much, suggesting they could have retained water. While the hints are exciting, the scientists say we can’t draw any final conclusions quite yet.
Bourrier said in the statement, “While our results suggest that the outer planets are the best candidates to search for water with the upcoming James Webb Space Telescope, 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.”