Water, methane found in atmosphere of nearby alien planet GJ 1132b

THE discovery of two new nearby ‘Goldilocks’ planets have raised fresh hopes of finding alien life. We’ve even detected air around one of them.

THE discovery of two new nearby ‘Goldilocks’ planets has raised hopes of finding alien life. We’ve even detected air around one of them.

At the heart of the hopes are Wolf 1061c, ‘only’ 14 light years distant from Earth, and GJ 1132b — a slightly more distant 39 light years away.

Both have been found to inhabit their star’s ‘Goldilocks zone’ — an orbital band where it is neither too hot nor too cold for liquid water to exist.

Wolf 1061c is one of three planets so far detected orbiting its M-Class Red Dwarf star. What makes this one so exciting is that it sits slap-bang in the centre of the habitable zone. But it does have a downside: it’s four times bigger than Earth, making it likely its gravity has created a ‘runaway greenhouse effect’ similar to that of Venus.

GJ 1132b is somewhat more promising. Its diameter is only 50 per cent bigger than that of Earth. Even though it sits on the warm end of the Goldilocks zone, its size could create conditions for a stable atmosphere. Now European astronomers say they have spotted one.

Known worlds in ‘goldilocks’ orbits. Source: NASA

In a study under review for publication by The Astrophysics Journaland reported on by Scientific American, the researchers say the European Southern Observatory in Chile detected traces of water and methane in what appears to be a thick atmosphere.

“We have shown that an Earth-mass planet is capable of sustaining a thick atmosphere,” says lead author astrophysicist John Southworth. “This is one step towards investigating whether a planet could host life.”

It’s not the first time an atmosphere has been found about an alien world. That was 15 years ago. But it is the first time one has been found around a smaller world — and not the equivalent of a Jupiter.

It’s exact composition, however, is yet to be determined.

GJ 1132b also orbits an M-Class Red Dwarf star — the most common type of star in our galaxy. It’s one of the smallest and coolest types of star, which makes its planets easier to separate from its own light.

Their suitability in sustaining life, however, is uncertain.

The discovery of stable, non-greenhouse atmospheres on planets orbiting red dwarf stars would be profound. They’re the most common star in the known galaxy. Picture: NASA

Being small, their planets tend to orbit closer and faster. This brings them within reach of flares. The planets also become ‘tidal locked’, with one face permanently looking towards the star in the same way the Moon always presents one face to Earth.

“Detecting the atmosphere of Earth-sized planets around M-dwarfs is an essential step in the search for habitable exoplanets,” study contributor Julien de Wit says.

“The concern, however, is that they may not always be able to sustain an atmosphere because of the potential history of strong activity of their star. Finding one with an atmosphere would provide us with hope.”

The researchers say bigger telescopes will be able to capture higher resolution images of the light passing through the planet’s atmosphere, enabling it to detect more of its components.