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This Ultracool Sun Could Be Shining On Alien Life

This article is more than 7 years old.

Astronomers have found the best chance for alien life close to Earth in the form of three potentially habitable worlds orbiting an ultracool dwarf star just 40 light years away.

Researchers using the TRAPPIST ((TRAnsiting Planets and PlanetesImals Small Telescope) at ESO’s La Silla Observatory spotted the planets in the habitable zone of their sun. They also determined that their size and temperature are similar to Earth and Venus, making them the best worlds ever found on which to search for life outside our Solar System.

“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, a postdoc in the Department of Earth, Atmospheric, and Planetary Sciences at MIT, in a statement.

“All of these things are achievable, and within reach now. This is a jackpot for the field.”

The 60cm TRAPPIST telescope is operated by the University of Liège, which together with astronomers from MIT and other international institutions, trained its sights on the 2MASS J23062928-0502285 star, also known as TRAPPIST-1. This dwarf star is about the size of Jupiter, around an eight the size of our own Sun, and much, much cooler.

TRAPPIST, which monitors infrared signals, observed the star’s light fade at regular intervals over the course of several months, indicating orbiting planets. Although these worlds are much closer to their sun than the planets of the Solar System, they aren’t superheated because the dwarf star is so cool.

The two innermost planets orbit in just one and a half and 2.4 days respectively, but they get only four and two times the amount of radiation as Earth. The third planet is a little harder to pin down, but is probably orbiting at an interval of four to 73 days, getting even less radiation than Earth. Given the size of the worlds and the level of radiation, all three could have regions with the right temperatures for liquid water and therefore extraterrestrial life.

“This really is a paradigm shift with regards to the planet population and the path towards finding life in the Universe. So far, the existence of such ‘red worlds’ orbiting ultra-cool dwarf stars was purely theoretical, but now we have not just one lonely planet around such a faint red star but a complete system of three planets!” said Emmanuël Jehin of the University of Liège, a co-author of the new study, in another statement.

Lead author Michaël Gillon, also of the University of Liège, explained that finding planets around these small, cool stars is the first place to look for life in the Universe, because these systems are the only place that current technology can study in detail.

To figure out if an exoplanet might harbour life, astronomers need to study the effect of its atmosphere on the light that reaches Earth. This effect is so small that it is lost for most Earth-sized planets orbiting distant stars, because the light of their suns is so bright. But with the ultracool TRAPPIST-1 sun, the effect should be able to be detected.

"Thanks to several giant telescopes currently under construction, including ESO’s E-ELT and the NASA/ESA/CSA James Webb Space Telescope due to launch for 2018, we will soon be able to study the atmospheric composition of these planets and to explore them first for water, then for traces of biological activity. That's a giant step in the search for life in the Universe," said de Wit.

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