For the first time ever, a team of astronomers from MIT, the University of Liège and other areas of the world has discovered three planets orbiting an ultracool dwarf star 40 light years from the Earth whose size and temperatures are similar to those seen on our planet and Venus, making them the best candidates for life outside our solar system thus far.
The team made the discovery using the 60-centimeter TRAnsiting Planets and PlanetesImals Small Telescope (TRAPPIST) based in Chile. This telescope is designed to focus on 60 nearby dwarf stars, which are invisible to optical telescopes. By analyzing dwarf stars at infrared wavelengths, TRAPPIST is able to search for planets in their proximity.
In the current study, TRAPPIST focused on the ultracool dwarf star 2MASS J23062928-0502285, which has now been named TRAPPIST-1. This star is approximately the size of Jupiter - around one-eighth that of our sun but significantly cooler.
Observations of TRAPPIST-1 revealed the presence of planets similar in size to Earth and Venus. The team revealed that the two innermost planets orbit the star in 1.5 and 2.4 days, although the radiation that they receive is only four and two times the amount, respectively, that the Earth receives from the sun. The third planet is believed to orbit the star anywhere from a range of four to 73 days and might receive less radiation than Earth.
All three planets likely possess regions with temperatures that are within a range - below 400 kelvins - for sustaining liquid water and life.
The close proximity of the system to the Earth - just 40 year light years away - means that scientists will soon be able to get a closer look at the planets' atmospheric compositions as well as their habitability and potential life.
"These planets are so close, and their star so small, we can study their atmosphere and composition, and further down the road, which is within our generation, assess if they are actually inhabited," said Julien de Wit of MIT and co-author of the study. "All of these things are achievable, and within reach now. This is a jackpot for the field."
"We will investigate what kind of atmosphere they have, and then will search for biomarkers and signs of life," he added. "We have facilities all over the globe and in space that are helping us, working from UV to radio, in all different wavelengths to tell us everything we want to know about this system. So many people will get to play with this [system]."
The findings were published in the May 2 issue of Nature.
