Planets with unusually dense atmospheres may support liquid water and possibly life on their surfaces. Even if the planet is drifting through space on its own rather than circling a star, the temperate conditions that permit liquid water may endure for billions of years.

Researchers made such a claim in their study, "Potential long-term habitable conditions on planets with primordial H-He atmospheres," in the journal Nature Astronomy.

NASA Telescope Reveals Seven Earth-sized Planets Around Single Star

(Photo : Photo digital Illustration by NASA/NASA via Getty Images)
UNSPECIFIED: In this NASA digital illustration handout released on February 22, 2017, an artist's concept allows us to imagine what it would be like to stand on the surface of the exoplanet TRAPPIST-1f, located in the TRAPPIST-1 system in the constellation Aquarius.

Rogue Planets With Odd Atmospheres, No Stars May Host Life

A planet beyond the solar system known as an exoplanet revolves around a star. Astronomers often consider the probability of liquid water being on their surfaces when evaluating their potential habitability.

"It was a vital ingredient in the emergence of life on Earth [and even] when we think of habitability in an alternative way, it is still difficult to replace liquid water as other solvents are not as suitable," said Lead author Marit Mol Lous at the University of Zürich in Switzerland mentioned via Forbes. "That is why we think the presence of liquid water is so essential to the possibility of life."

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Oxygen and nitrogen, which make up the majority of the atmosphere on Earth, are other elements that astronomers look for. The new modeling is presented in the research. 

However, the result indicates that planets with their original primordial atmospheres of hydrogen and helium, which the Earth also formerly possessed, might be theoretically livable for lengthy periods.

of hydrogen and helium, which the Earth also formerly possessed, might be theoretically livable for lengthy periods.

How Experts Examined These Atmospheres

The majority of planetary systems might be different from Earth, according to earlier research that examined far-off worlds. Super-Earths are rocky planets up to 10 times the mass of Earth, are not found in our solar system but are highly prevalent elsewhere.

Mol Lous told Space.com that the exoplanets they discovered are distinct from the planets in our solar system, which is a compelling case for continuing to consider unconventional theories on habitability.

Researchers examined whether super-Earths might sustain life in the latest study. Because they are the easiest to notice, astronomers have only so far found super-Earths that orbit close to their stars. Though many super-Earths could orbit distant from their stars, this idea has been supported by earlier computer simulations of planet formation.

Super-Earths that are far from their stars could still have a significant amount of the hydrogen and helium gas that formerly made up the majority of their planetary systems. Around 99.9 percent of the known normal things in the universe consist of hydrogen and helium combined. The heat from a star would evaporate these gases from any super-Earth nearby. Still, super-Earths distant from a star may retain this primordial atmosphere.

Researchers in the latest study looked into the possibility of life on a super-Earth engulfed by these gases. Scientists noticed while the planet is far away, if the atmosphere of such a world is large enough, its hydrogen can act as a greenhouse gas.

The researchers created computer models of super-Earths with atmospheres rich in hydrogen and helium that orbited sun-like stars at distances of one to one hundred astronomical units and were between one and 10 times as massive as Earth (AUs). The average distance (one AU), or around 93 million miles or 150 million kilometers, between the Earth and the sun

The scientists discovered that super-Earths at distances higher than 2 AU were capable of supporting temperate temperatures and liquid water on their surfaces for up to 5-8 billion years. Such findings imply that while examining the habitability of distant planets, researchers should also consider exotic environments.

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