Scientists say that water worlds – planets with deep, international oceans – could be pretty frequent in our Milky Way galaxy. These worlds would have much more water than Earth. Might something reside there? And will we detect it if it did? On January 3, 2024, a world group of researchers said in a brand new paper that up to date evaluation of exoplanet LHS 1140 b – solely 50 light-years from Earth – confirmed it to be a potential water world. Or it’s a mini-Neptune. Scientists aren’t fairly certain.
The researchers published their new peer-reviewed findings in The Astrophysical Journal Letters on January 3, 2024.
Meet LHS 1140 b
The planet orbits a small red dwarf star, LHS 1140, about 50 light-years from Earth within the constellation Cetus. It orbits throughout the habitable zone of its star, the area the place temperatures could enable liquid water to exist. Astronomers first detected it in 2017 utilizing the transit method. This methodology appears to be like for exoplanets crossing in entrance of their stars as seen from our vantage level right here on Earth.
LHS 1140 b is just one.7 occasions the radius of Earth and completes an orbit round its star in simply 24.7 days.
Water world?
As a consequence of its measurement in comparison with Earth, and primarily based on earlier research, astronomers thought LHS 1140 b was in all probability a rocky planet, a super-Earth. Nevertheless, as Pultarova wrote at House.com:
However a brand new evaluation of all obtainable observations has proven that LHS 1140 b shouldn’t be dense sufficient to be purely rocky and should both comprise far more water than Earth or possess an intensive ambiance full of sunshine components corresponding to hydrogen and helium.
Because of this the planet, as an alternative of being largely rocky, could possibly be a water world with extra water than Earth. Or it might be a mini-Neptune with an environment of hydrogen and helium. However which is it? Scientists don’t know but.
The paper stated that if the planet is a water world, then:
A possible outer water layer on this planet is most probably to be in both a frozen or a liquid state, because the planet resides within the water condensation zone. We thus assume the atmospheric layer of LHS 1140 b to be an Earth-like ambiance with a floor strain of 1 bar.
A variant of this mannequin is the Hycean world … a water world surrounded by a skinny H/He-rich layer, as was lately proposed for the temperate mini-Neptune K2-18 b.
If it’s a water world, then might it’s liveable? Tereza Pultarova wrote concerning the newest findings for House.com on January 11, 2024. And lead writer Charles Cadieux on the College of Montreal in Quebec, Canada, instructed House.com:
For the reason that planet is within the liveable zone, it’s actually attention-grabbing, as a result of for those who had water on the floor of a planet contained in the liveable zone, you’ll anticipate that a number of the water is within the liquid state. In order that’s a extremely attention-grabbing situation when it comes to habitability.
Or a mini-Neptune?
The opposite risk is that LHS 1140 b is a mini-Neptune. It might have a core much like Earth’s however have a hydrogen-poor ambiance. In contrast to most different mini-Neptunes, it could have solely a skinny hydrogen and helium ambiance. Because the paper said:
The planet is both a novel mini-Neptune with a skinny ~0.1% hydrogen-helium ambiance or a water world with a water mass fraction within the 9%-19% vary relying on the atmospheric composition and the iron-magnesium ratio of the planetary inside.
Water world with ice shell and geysers?
LHS 1140 b was additionally considered one of 17 exoplanets planets featured in a NASA study revealed final month. The examine steered that these identified exoplanets could have oceans lined by an ice shell. That is paying homage to some moons in our solar system, corresponding to Europa and Enceladus. Additional, these worlds might have sufficient inside warmth for geysers to erupt via the ice crust. In that case, that sounds rather a lot like what is going on on Enceladus, with its well-known south pole geysers that NASA’s Cassini spacecraft found. There may be additionally rising proof for geysers on Europa, however they appear to be much less frequent and on a smaller scale than Enceladus’ geysers.
The estimated thickness of an ice shell on LHS 1140 b is about one mile (1.6 km). The researchers additionally estimated the geyser exercise to be about 639,000 kilos/second (290,000 kg/sec) of water and different materials ejected into space. Lead writer Lynnae Quick of NASA’s Goddard House Flight Heart in Greenbelt, Maryland, stated:
Since our fashions predict that oceans could possibly be discovered comparatively near the surfaces of Proxima Centauri b and LHS 1140 b, and their charge of geyser exercise might exceed Europa’s by tons of to 1000’s of occasions, telescopes are most probably to detect geological exercise on these planets.
Webb telescope would possibly give us a solution
Proper now, it’s troublesome to find out which sort of planet LHS 1140 b is. We’d like extra detailed evaluation. NASA’s James Webb House Telescope might present that extra information and decide which situation is appropriate. Pulatrova wrote in House.com:
Cadieux stated the researchers have utilized to review the LHS 1140 system with JWST to research whether or not the exoplanet has an environment stuffed with hydrogen and helium or whether or not it seems to have an abundance of water. Thus far, nonetheless, no observations have been deliberate.
Backside line: A brand new examine says that an exoplanet 50 light-years away is both a water world or a mini-Neptune. NASA’s Webb telescope would possibly inform us which it’s.
Source: Prospects for Cryovolcanic Activity on Cold Ocean Planets
Read more: Did Webb find signs of life on exoplanet K2-18 b?
Read more: Water worlds may be abundant in our galaxy
