A distant alien world dubbed k2-18b and located 124 light-years away from Earth could be a massive ocean world with the necessary conditions to support life as we know it.
Although it is one of the more than 4,000 exoplanets that have been discovered to date, this distant world is special because scientists have revealed that it meets the necessary conditions to support life as we know it.
In fact, for all we know, life has developed on the planet just as on Earth.
The exoplanet, which is a rocky world with a density between that of Earth and Neptune, is called K2-18b, and it was discovered in 2015 and rose to fame last September when two different teams announced in the journal Nature Astronomy the discovery of water vapor in the exoplanet’s atmosphere.
This alien planet has become one of the various exoplanets that have been found to date by astronomers which could support life as we know it.
K2-18b orbits its host star in the so-called habitable zone (also known as the Goldilocks zone), which means that it is just at the right distance from its stars so temperatures on the surface allow liquid water to exist.
Now, if there is liquid water in abundance on the surface, it could mean good changes for life as we know it to exist there too.
However, and despite the fact that astronomers have discovered the planet’s orbit in a habitable zone, the extent of its atmosphere and what lies beneath it remained a mystery.
Now, a team from the University of Cambridge has used the mass, radius and atmospheric data of the exoplanet to unveil unprecedented details about the exoplanet.
The astronomers have determined that indeed, this world is promising when it comes down to alien life.
According to the new study published in the Astrophysical Journal Letters, K2-18b could meet the necessary conditions to support alien life, and could even be a massive, oceanic world.
“Water vapor has been detected in the atmospheres of a number of exoplanets but, even if the planet is in the habitable zone, that doesn’t necessarily mean there are habitable conditions on the surface,” revealed Dr. Nikku Madhusudhan from Cambridge’s Institute of Astronomy, who led the new research.
“To establish the prospects for habitability, it is important to obtain a unified understanding of the interior and atmospheric conditions on the planet – in particular, whether liquid water can exist beneath the atmosphere.”
Given the size of K2-18b with an estimated radius of 2.6 times and 8.6 times the mass of the Earth, it has been suggested that it would be more like a smaller version of Neptune than a larger version of the Earth.
A mini-Neptune is expected to have a significant hydrogen “envelope” that surrounds a layer of high-pressure water, with an inner core of rock and iron.
If the hydrogen envelope is too thick, the temperature and pressure on the surface of the water layer below would be too large to support life. However, Dr. Madhusudhan and fellow colleagues have demonstrated that despite the size of K2-18b, its hydrogen envelope is not necessarily too thick and the water layer could have the right conditions to support life as we know it.
To come to these conclusions the scientists used existing observations of the atmosphere, as well as mass and radius, to determine the composition and structure of the atmosphere and interior. To explain the data, they used detailed numerical models and statistical methods.
The new study has confirmed that K2-18b’s atmosphere is hydrogen-rich with a significant amount of water vapor. Interestingly, the astronomers also discovered that levels of other chemicals such as methane and ammonia were lower than anticipated for such an atmosphere. Whether these levels can be connected to biological processes in the distant world remains to be seen.