They have studied a world known as GJ 1132b, which is 1.4-times the size of our planet and lies 39 light years away.
Their observations suggest that GJ 1132b the “super-Earth” is cloaked in a thick layer of gasses that are either water or methane or a mixture of both.
The study is published in the Astronomical Journal.
Discovering an atmosphere, and characterizing it, is an important step forward in the hunt for life beyond our Solar System.
But it is highly unlikely that this world is habitable: it has a surface temperature of 370C.
Dr John Southworth, the lead researcher from Keele University, said: “To my knowledge the hottest temperature that life has been able to survive on Earth is 120C and that’s far cooler than this planet.”
The discovery of planet GJ 1132b was first announced in 2015. It lies in the Vela constellation in the southern hemisphere.
While it is a similar size to Earth, the star it orbits is much smaller, cooler and dimmer than our Sun.
Using a telescope at the European Southern Observatory in Chile, the researchers were able to study the planet by watching how it blocked some of the light of its host star as it passed in front of it.
“It makes the star look a little bit fainter – and it’s actually a very good way of finding transiting planets – it’s how this one was found,” said Dr Southworth.
But different molecules in a planet’s atmosphere – if it has one – absorb light in different ways, allowing scientists to look for their chemical signatures when the world transits its star.
The observations of planet GJ 1132b suggest that it has a thick atmosphere containing either steam and/or methane.
“One possibility is that it is a ‘water world’ with an atmosphere of hot steam,” said Dr Southworth.
The researchers say while it is unlikely that any life-forms could survive on this world, the discovery of an atmosphere is encouraging in the hunt for extraterrestrial life.
Dr Southworth said: “What we have shown is that planets around low mass stars can have atmospheres and because there are so many of those in the Universe, it makes it that much more likely that one might have life.”
Commenting on the research Marek Kukula, the public astronomer at the Royal Observatory Greenwich, said: “This is a nice proof of concept.
“If the technology can detect an atmosphere today, then it bodes well for being able to detect and study the atmospheres of even more Earth-like planets in the not-too-distant future.”
Gliese 1132 b
Gliese 1132 b (often shortened to GJ 1132 b) is an exoplanet orbiting a red dwarf star (Gliese 1132) 39 light years (12 parsecs) from Earth. The planet is considered uninhabitable but cool enough to possess an atmosphere. Gliese 1132 b was discovered by the MEarth-South array in Chile.
It has been called “one of the most important planets ever discovered beyond the Solar System”: Due to its relative proximity to Earth, telescopes should be able to determine the composition of its atmosphere, the speed of its winds and the color of its sunsets. This is due in part to the small diameter of its parent star (21% that of the Sun), which increases the effect on the star’s light of its transits. The planet’s diameter is approximately 20% larger than that of the Earth and its mass is estimated at 1.6 times that of Earth, implying that it has an Earth-like rocky composition. Gliese 1132 b orbits its star every 1.6 days at a distance of 1.4 million miles.
The planet receives 19 times more stellar radiation than Earth. The temperature of the top of its atmosphere is estimated at 500 °F (260 °C; 533 K). The planet is estimated to be hotter than Venus, as higher temperatures may prevail near the surface. (cf. Atmosphere of Venus, Colonization of Venus) It is possible that one side of the planet is cooler, because it is presumed to be tidally locked due to its proximity to its star; however, under most circumstances where an atmosphere is thick, it would be able to transfer heat to the far side.
In April 2017, at atmosphere was confirmed around Gliese 1132 b. It is the most Earth-like exoplanet to date that is known to have an atmosphere.
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