Abstract Concept of TRAPPIST-1 System

Abstract Concept of TRAPPIST-1 System

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News release ID: STScI-2018-07
Release Date: Feb 5, 2018
Image Use: Copyright
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This artist's concept appeared on the Feb. 23, 2017 cover of the journal Nature announcing that the nearby star TRAPPIST-1, an ultra-cool dwarf, has seven Earth-sized planets orbiting it. Two of the planets were discovered in 2016 by TRAPPIST (the Transiting Planets and Planetesimals Small Telescope) in Chile. NASA’s Spitzer Space Telescope and several ground-based telescopes uncovered five additional ones, increasing the total number to seven. The TRAPPIST-1 system is located about 40 light-years from Earth.

Astronomers have used NASA's Hubble Space Telescope to conduct the first spectroscopic survey of the Earth-sized planets (d, e, f, and g) within TRAPPIST-1's habitable zone. The habitable zone is a region at a distance from the star where liquid water, the key to life as we know it, could exist on the planets’ surfaces. This spectroscopic survey is a follow-up to Hubble observations made in 2016 of the atmospheres of the inner TRAPPIST-1 planets b and c. Hubble reveals that at least three of the exoplanets (d, e, and f) do not seem to contain puffy, hydrogen-rich atmospheres similar to gaseous planets such as Neptune. Additional observations are needed to determine the hydrogen content of the fourth planet’s (g) atmosphere. Hydrogen is a greenhouse gas, which smothers a planet orbiting close to its star, making it hot and inhospitable to life. The results, instead, favor more compact atmospheres like those of Earth, Venus, and Mars.

Artwork, Exoplanets


Artist's Concept: NASA and JPL/Caltech
Science: NASA, ESA, J. de Wit (MIT), H. Wakeford (University of Exeter/STScI), and N. Lewis (STScI)