Nearby exoplanet could be first known ocean world: Webb telescope

Scientists using the James Webb Space Telescope claim that a planet relatively close to Earth is the first planet ever found with a liquid ocean that could potentially support life outside our solar system.

More than 5,000 planets have been discovered outside the solar system so far, but only a handful of them are in the so-called ‘Goldilocks zone’: not too hot and not too cold. This zone could contain liquid water, a key ingredient for life.

The exoplanet LHS 1140 b is one of the few planets in this habitable zone and has been thoroughly studied since its discovery in 2017.

The distance between the Sun and Earth is 48 light years, which is over 450 trillion kilometers (280 trillion miles). Considering the vast distances in space, this is relatively close.

The exoplanet was thought to be a small gas giant, a so-called ‘mini-Neptune’, with an atmosphere too thick with hydrogen and helium to support extraterrestrial life.

However, new observations from the Webb telescope have confirmed that the exoplanet is in fact a rocky ‘super-Earth’.

According to a study published Wednesday night in the journal Science, it is 1.7 times larger than Earth but has 5.6 times the mass. The letters of the astrophysical journal.

‘Best bet’ for the ocean 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, ruling out the planet as a mini-Neptune.

The planet’s density indicates that “there are actually large amounts of water present,” study co-author Martin Turbet of the French scientific research centre CNRS told AFP.

It could really be an immense amount of water.

All the water in Earth’s oceans represents only 0.02 percent of its mass. Only 10 to 20 percent of the exoplanet’s mass was estimated as water.

Whether this water is liquid or icy depends on the planet’s atmosphere.

“We have no direct evidence that there is an atmosphere, but several elements point in that direction,” Turbet said.

Charles Cadieux, lead author of the study and a PhD candidate at the University of Montreal, said that “of all the currently known temperate exoplanets, LHS 1140 b may offer the best chance to one day indirectly confirm the presence of liquid water on the surface of an alien world.”

On the positive side, the planet is slowly being warmed by its red dwarf star, which is one-fifth the size of the Sun.

According to Turbet, the exoplanet’s surface temperature will be much the same as that of Earth and Mars.

The presence of gases such as carbon dioxide plays an important role in determining whether the planet is covered in ice or water.

Ocean with a bull’s eye

One possibility is that the surface is mostly ice, but that where the planet is most exposed to the heat of its star, there is a vast liquid ocean.

Models suggest this ocean could be about 4,000 kilometers in diameter, about half the area of ​​the Atlantic Ocean.

Or the liquid water could be hidden beneath a thick layer of ice, as on the moons Ganymede, Enceladus or Europa, which orbit Jupiter and Saturn.

Cadieux said Webb’s instrument detected signs that indicated “the presence of nitrogen,” adding that more research is needed to confirm the finding.

Nitrogen is found everywhere on Earth and is considered a possible building block for life.

The researchers hope to use a few more hours of the Webb telescope’s valuable time to learn more about LHS 1140 b.

The researchers estimate that it will take at least a year before it can be confirmed whether the exoplanet has an atmosphere, and another two or three years before the presence of carbon dioxide can be detected.

© 2024 AFP