Newly-discovered exoplanet could be best clue to life out there

Phillip Butler
April 20, 2017

Finding these new Earths is all very well but it's also becoming critical that we focus on looking after the most super-Earth of all - ours. That make this place an exciting candidate in the search for life outside our Solar System.

But an atmosphere around a habitable M-dwarf planet has never been spotted. A newly discovered "super-Earth" orbiting in the habitable zone of a nearby small star, has catapulted itself to the top of that list.

Artist's impression of the super-Earth exoplanet LHS 1140b.

So, if there is water, the stuff of life, it can exist encouragingly in liquid form and not as rock-solid ice or vapour. They measured the mass of the planet to be 6.6 times that of Earth, which is consistent with a rocky bulk composition. But they're not always ripe for life. This planet is so dense that it must be rocky, the thinking goes.

The MEarth-South telescope array. But what exactly do we know about LHS 1140b that suggests it has an atmosphere?


Follow-up observations studied the star's "wobble" caused by a gravitational tug of war with the planet and confirmed the presence of a super-Earth. That, combined with the planet's estimated size, indicates this world is rocky. "But we know that things can live at very high pressures at the bottom of the ocean, and we know of lots of bacteria that can survive all sorts of insane environments, so I think it's not infeasible to imagine some form of life being ok with living on a super-Earth". "We found a planet that we can actually study that might be actually Earth-like".

In the future, they want to use HARPS to continue observing the star and see if there are more planets around it. But if LHS 1140b was able to withstand the brunt of its star's radiation, it's possible signs of life are lurking there. Those planets are smaller than this one, but they're thought to be rocky too.

This habitable zone is also known as the "Goldilocks" zone, taken from the children's fairy tale.

"The LHS 1140 system might prove to be an even more important target for the future characterization of planets in the habitable zone than Proxima b or TRAPPIST-1", researchers Xavier Delfosse and Xavier Bonfils said. That also means the habitable zone is much closer to the star. "LHS 1140 is brighter at optical wavelengths because it's slightly bigger than the TRAPPIST-1 star". Such flaring can strip nearby planets of their atmospheres and douse them with solar radiation, making them inhospitable to biological life. The distance between LHS1140b and its host star is about 8 percent of the distance between Earth and the Sun, but the amount of high-energy radiation it receives is still relatively low. "We plan to search for water, and ultimately molecular oxygen". That makes it much it easier to see and study this planet, since it's not completely overpowered by intense starlight. "Perhaps there's a limit for what life can handle when the gravity gets too high", says Dittmann. It is located in the constellation Cetus, 39 light years or 230 trillion miles away. Figuring out the gases in that atmosphere could paint a picture of what conditions are like on the surface below. "It turns out it was lurking there all along", says Dittmann, now at MIT. Between them, as Didier Queloz, who co-led the discovery of the TRAPPIST-1 system, has said, "You can now move on from talking about the possibility of life on other planets to measuring the data on the planets". TRAPPIST-1 is just a little too dim to do this, Dittmann argues. Once it's completed, JWT will be the most powerful space-based telescope ever deployed - it will be used to peer into the atmospheres of all of these planets and more.

Right now, LHS 1140b looks like an attractive target for further observation.

Other reports by Ligue1talk

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