Will this super-Earth become a habitable place for humans in the future?

Astronomers have discovered water vapor in the atmosphere of a rocky planet for the first time. Interestingly, the planet is located in the so-called habitable zone of its star, one of the most promising places in the galaxy to search for signs of alien life.

Illustration: Artist’s impression of K2-18b. Illustration: ESA/Hubble, M. Kornmesser

The planet K2-18b is located 110 light-years away and was discovered by the Kepler space observatory in 2015. Preliminary scans of the exoplanet suggest it is a super-Earth, meaning a rocky planet larger than Earth that has an atmosphere. These observations, coupled with the fact that K2-18b lies within the habitable zone (the sweet spot in a star system where water is likely to exist in liquid form), warrant further study.

Using the Hubble Space Telescope, a team from University College London performed spectroscopic measurements of K2-18b's atmosphere and discovered a unique water signature. Details of this important discovery are published in the journal Nature.

Angaelos Tsiaras, an astronomer at University College London and one of the authors of the study, announced on a press conference call that this is the first time water vapor has been found on a planet that is not a gas giant. It is the first discovery of its kind - a planet orbiting within the habitable zone - and the only Earth-like planet we know of outside our solar system... He added: "As far as we know, it is the best Where humans live. ”

Water vapor has been found in exoplanets before, but only in gas giants. The possibility that K2-18b is an ice giant similar to Neptune or Uranus is very small. The greater possibility is that it is a super-Earth. Astronomers can only see the exoplanet's upper atmosphere, but it is twice the size of Earth and eight times more massive. Importantly, its density is similar to Mars and three times that of typical gas giant planets. This led scientists to conclude that K2-18b may be an Earth-like planet characterized by a solid rocky core.

K2-18b orbits a dim red dwarf star and takes only 33 days to complete one orbit of its host star. At such a close distance, it may not sound like K2-18b is in the habitable zone, but because red dwarfs emit lower levels of radiation, their habitable zone is much closer than that of galaxies like ours. Researchers noted in a news release that K2-18b receives about the same amount of radiation as Earth and has temperatures similar to what we experience here.

Unfortunately, exoplanets orbiting red dwarf stars are considered uninhabitable because such stars tend to produce extremely powerful and frequent solar flares. As Tsiaras pointed out during the press conference, conditions on K2-18b are likely to be "harsh" compared to Earth. Hubble observed a clear signal of water, but researchers at University College London are not sure how much water is in K2-18b's atmosphere or whether liquid water exists on its surface. Through a series of models, scientists have shown that K2-18b's atmosphere may contain only 0.01% water, or as much as 50% water.

This is obviously a huge difference.

Giovanna Tinetti, another author of the study, explained in response to a question posed by Gizmodo that the reason for such a large range is that Hubble can only detect water signals in the spectrum , and "it's difficult to quantify the amount of water compared to other molecules." But Tinetti told a news conference that the signal from the water was "very strong," regardless of the amount. Future research will focus on narrowing this large disparity, she said.

An interesting feature of super-Earths is that most of them are likely to be water worlds - Earth-like planets completely covered by deep global oceans. When Gizmodo asked Tinetti if it was possible that K2-18b could have been a water world, she said that it was a "good possibility" given the model results, but that the current data could neither confirm nor rule it out.

Li Zeng, a planetary scientist at Harvard University who was not involved in the study, said the results were "not surprising" because he expected that many exoplanets similar in size to K2-18b would have "large parts of their interiors." There is water," he told Gizmodo in an email. He said the study is consistent with his own work. Earlier this year, Li and his colleagues presented evidence that the oceans of super-Earth water worlds could be hundreds or even thousands of kilometers deep.

In addition to water, Hubble also discovered traces of hydrogen, a discovery that aroused the interest of Tom Louden, a physicist at the University of Warwick and an expert in extraterrestrial atmospheres. Louden said the paper's results are "exciting" and "significant in determining the evolutionary history of exoplanet atmospheres." At the same time, however, Louden said the findings could deal a blow to Earth's potential to harbor life. Louden said in an email to Gizmodo: "The results suggest that the planet K2-18b retains some, or perhaps all, of its 'primary atmosphere' composed of hydrogen and helium that it collected during its formation.

This suggests that the radiation from the star is not stripping away its atmosphere too strongly or effectively, which is probably good news since we expect many Earth-like planets to exist around this type of star. Because it could mean their atmospheres could remain stable."

At the same time, the news also poses potential hazards to human habitability. He said that if "most planets are born with a very large atmosphere of hydrogen and helium that they cannot escape, this could make the development of complex life more difficult - we just don't know enough at this stage." /p>

In a press conference, Ingo Waldmann discussed how the primordial gases on K2-18b affected Earth's ability to support life.

"A hydrogen atmosphere is habitable. "Based on theoretical models, there's no reason not to think so," he said. He noted that our current bias toward habitability is very "Earth-centric," which makes sense because the Earth is where we live. The only habitable planet we know. Therefore, Waldmann said, future research should investigate the habitability of a hydrogen-rich environment.

Clearly, K2-18b is a good or bad planet in terms of its ability to host life. A mixed bag. Like Earth, it has a temperate climate, a rocky core, and water. The flip side is that K2-18b is in orbit around a potentially dangerous red dwarf star, and its atmosphere is filled with primordial gases. Not to mention its huge size and mass compared to Earth, which is an unknown variable for habitability

This exoplanet is a curious and fascinating one for future research. topic, but one thing remains very clear: the search for true Earth-like planets continues

References

1. WJ Encyclopedia

2. .Astronomical terms

3. gizmodo-George Dvorsky-orange

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