Hubble Space Telescope astronomers have conducted the first search for atmospheres around temperate, Earth-sized planets beyond our solar system and found indications that increase the chances of habitability on two exoplanets.
Specifically, they discovered that the exoplanets TRAPPIST-1b and TRAPPIST-1c, approximately 40 light-years away, are unlikely to have puffy, hydrogen-dominated atmospheres usually found on gaseous worlds.
“The lack of a smothering hydrogen-helium envelope increases the chances for habitability on these planets,” said team member Nikole Lewis of the Space Telescope Science Institute (STScI) in Baltimore. “If they had a significant hydrogen-helium envelope, there is no chance that either one of them could potentially support life because the dense atmosphere would act like a greenhouse.”
Julien de Wit of the Massachusetts Institute of Technology in Cambridge, Massachusetts, led a team of scientists to observe the planets in near-infrared light using Hubble’s Wide Field Camera 3. They used spectroscopy to decode the light and reveal clues to the chemical makeup of an atmosphere. While the content of the atmospheres is unknown and will have to await further observations, the low concentration of hydrogen and helium has scientists excited about the implications.
“These initial Hubble observations are a promising first step in learning more about these nearby worlds, whether they could be rocky like Earth, and whether they could sustain life,” says Geoff Yoder, acting associate administrator for NASA’s Science Mission Directorate in Washington. “This is an exciting time for NASA and exoplanet research.”
Julien de Wit, Hannah R. Wakeford, Michaël Gillon, Nikole K. Lewis, Jeff A. Valenti, Brice-Olivier Demory, Adam J. Burgasser, Artem Burdanov, Laetitia Delrez, Emmanuël Jehin, Susan M. Lederer, Didier Queloz, Amaury H. M. J. Triaud, Valérie Van Grootel. A combined transmission spectrum of the Earth-sized exoplanets TRAPPIST-1 b and c. Nature, 2016http://dx.doi.org/10.1038/nature18641