All the water in Earth’s oceans makes up just 0.02 percent of its mass (Representational)
Paris:
A planet relatively close to Earth could be the first ever detected with a potentially life-sustaining liquid ocean outside our Solar System, according to scientists using the James Webb Space Telescope.
More than 5,000 planets have been discovered outside the Solar System so far, but only a few are in the so-called “Goldilocks zone” – neither too hot nor too cold – which could harbor liquid water, a key ingredient for life. .
The exoplanet LHS 1140 b is one of the few in this habitable zone and has been closely scrutinized since it was first discovered in 2017.
It is located 48 light years from Earth, which is equivalent to more than 450 billion kilometers (280 billion miles) – relatively close in the vast distances of space.
The exoplanet was thought to be a small gas giant called a “mini-Neptune,” with an atmosphere too dense with hydrogen and helium to support alien life.
However, new observations from the Webb telescope have confirmed that the exoplanet is actually a rocky “super-Earth.”
It is 1.7 times larger than Earth but has 5.6 times its mass, according to a study published Wednesday in The Astrophysical Journal Letters.
‘Best bet’ for oceanic world
The Webb telescope was able to analyze the planet’s atmosphere as it passed in front of its star.
There were no signs of hydrogen or helium, which ruled out the planet being a mini-Neptune.
The planet’s density indicates that it “actually has large amounts of water”, study co-author Martin Turbet of France’s CNRS scientific research center told AFP.
It could be a truly immense amount of water.
All the water in Earth’s oceans represents just 0.02% of its mass. But it’s estimated that 10 to 20 percent of the exoplanet’s mass is water.
Whether or not this water is in liquid or icy form depends on the planet’s atmosphere.
“We don’t have direct evidence that it has an atmosphere, but several elements point in that direction,” said Turbet.
The study’s lead author, Charles Cadieux, a PhD student at the University of Montreal, said that “of all the currently known temperate exoplanets, LHS 1140 b could very well be our best bet to one day indirectly confirm liquid water on the surface of one.” alien world.”
One positive aspect is that the planet is gently warmed by its red dwarf star, which is a fifth the size of the Sun.
The exoplanet’s surface temperature should be quite similar to that of Earth and Mars, Turbet said.
The presence of gases such as carbon dioxide will play a key role in determining whether the planet is covered in ice or water.
Ocean in target
One possibility is that the surface is mostly icy, but there is a vast liquid ocean where the planet is most exposed to the heat of its star.
This ocean could measure about 4,000 kilometers in diameter, about half the surface area of the Atlantic Ocean, the modeling suggested.
Or liquid water could be hidden beneath a thick layer of ice, as on the moons Ganymede, Enceladus or Europa, which orbit Jupiter and Saturn.
Webb’s instrument detected signals that suggest “the presence of nitrogen,” Cadieux said, adding that more research is needed to confirm the discovery.
Nitrogen is found everywhere on Earth and is considered another potential ingredient for life.
Researchers hope to squeeze a few more hours of precious Webb telescope time to discover more about LHS 1140 b.
It will take at least a year to confirm whether the exoplanet has an atmosphere and another two or three to detect the presence of carbon dioxide, the researchers estimated.
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