A team of astronomers have discovered a system of three Earth-like exoplanets orbiting a small star that is only 40 light-years away from Earth, that are considered good candidates for supporting life.
The star in question, an ultracool dwarf called TRAPPIST-1, is only a bit bigger than Jupiter, and only emits approximately one two-hundredths of the output of our Sun, making it too faint to see with the naked eye. The planets in question, however, orbit very close to the star, allowing them to gather enough light from the star to keep warm. Because of their extremely close orbits, the planets orbit TRAPPIST-1 extremely quickly: the innermost planet takes 1.5 Earth days for a single revolution, and the second planet’s year is only 2.4 days.
"These are not massive, hot, super exotic worlds," says study member and MIT postdoctoral associate in planetary science Julien de Wit. "All three of them are close to one Earth [radius], and each of them could be suitable for life." Most known exoplanets are much larger than the Earth, with many of them being gas giants, as the occlusion they create as they pass in front of their host star is typically easier to spot.
TRAPPIST-1’s low temperature is also expected to make attempts at determining the chemical makeup of the planets’ atmospheres easier, as the brightness of the stars that are host to most known exoplanets tend to drown out their spectrographic signatures. Astronomer Nikole Lewis, with the Space Telescope Science Institute, is looking forward to studying TRAPPIST-1’s planets with the James Webb Space Telescope, scheduled to launch in 2018. "These will be the first truly Earth-sized planets with temperatures that span the same temperatures of rocky planets in our solar system that we can study with JST."