NASA confirms existence of exoplanet with oceans and hints of life
A distant exoplanet known as K2-18 b is likely to have open oceans in liquid form that could be a haven for marine life. This was confirmed by observations by an international team of astronomers thanks to NASA's James Webb Telescope (JWST).
This is stated in a paper to be published in the scientific journal The Astrophysical Journal Letters. A preview of the material was published on the portal of the European Space Agency (ESA), dedicated to the JWST telescope.
Exoplanet K2-18 b is 8.6 times more massive than Earth. Previous observations have revealed the presence of carbon-containing molecules, particularly methane and carbon dioxide, in its atmosphere. Other studies have also suggested that this exoplanet is of the Hycean type, meaning it has a hydrogen-rich atmosphere and a surface covered by a water ocean.
The first studies of K2-18 b were conducted back with the Gabble Space Telescope and prompted further research that changed the understanding of this system.
K2-18 b orbits in a suitable zone for life in the cold dwarf star K2-18. This system is located in the constellation of Leo at a distance of 120 light-years from Earth.
As scientists point out, exoplanets like K2-18 b, which are between the size of Earth and Neptune, are unlike anything in our solar system. This means that they are poorly understood, and the nature of their atmospheres is a subject of active debate among astronomers.
That K2-18 b could be a Hycean-type exoplanet is intriguing to astronomers, as scientists consider these particular worlds to be promising environments for searching for evidence of life on exoplanets.
"Our results emphasize the importance of considering a variety of suitable environments when searching for life anywhere," explained Nikku Madhusudhan, an astronomer at the University of Cambridge and lead author of the paper, in an explanation of the new observations.
Traditionally, he said, the search for life on exoplanets has focused on smaller, rocky planets, but large Hycean planets are "much more favorable for atmospheric observations."
The large amounts of methane and carbon dioxide and lack of ammonia support the hypothesis that an ocean may exist beneath the hydrogen-rich atmosphere on K2-18 b. The JWST observation also identified a molecule called dimethyl sulfide (DMS), which on Earth is produced only by living organisms. Specifically, by phytoplankton in the marine environment.
However, scientists cautioned against drawing any conclusions about DMS, calling the data on this molecule less reliable and requiring further verification.
"Upcoming JWST observations will be able to confirm whether DMS is indeed present in the atmosphere of K2-18 b at significant levels," Madhusudhan said.
The scientists also noted that the mere fact that K2-18 b is in a suitable zone for life and contains carbon-containing molecules does not necessarily mean that the planet can support life.
They explained that the planet's large size - its radius is 2.6 times that of Earth - means that its interior probably contains a large mantle of high-pressure ice, like Neptune's, but with a thinner, hydrogen-rich atmosphere and ocean surface. Such a world would be expected to have oceans, but they might be too hot to be habitable or in a liquid state.
In the future, the scientists intend to conduct studies using the Mid-InfraRed Instrument (MIRI) spectrograph that JWST is equipped with. They hope the new study will confirm their findings and provide new insights into the environmental conditions on K2-18 b.
"Our ultimate goal is to identify life on a habitable exoplanet, which would change our understanding of our place in the universe. Our results are a promising step towards a deeper understanding of Hycean worlds in this search," Madhusudhan summarized.
Earlier OBOZREVATEL also told about the fact that the NASA telescope showed a bright death agony of a distant star.