Article by: Andacs Robert Eugen, on 01 July 2022, at 02:55 am Los Angeles time

Living conditions, as we know them, may not be limited to Earth-like planets, and now scientists have determined a type of exoplanet that has the potential to be habitable for billions of years.

The key is to keep the liquid water on its surface for a long time. Here on Earth, the presence of liquid water was vital to the emergence of life. By extension, exoplanets that may be able to retain liquid water may be more likely to favor life as we understand it today.

New research coordinated by astronomer Marit Mol Lous of the University of Zurich, Switzerland, concludes that a dense atmosphere of hydrogen and helium can maintain temperatures and conditions suitable for life for a very long time.

"One of the reasons why water can be liquid on Earth is its atmosphere," says theoretical astrophysicist Ravit Helled of the University of Zurich, Switzerland. "With its natural greenhouse effect, it captures exactly the right amount of heat to create the right conditions for the formation of oceans, rivers, and rains."

However, the Earth's atmosphere did not always look the way it does today. Now it consists mainly of nitrogen, followed by oxygen, with only traces of hydrogen and helium.

When the planet was newly formed, it had what is called a primordial atmosphere, composed mainly of hydrogen and helium: the main constituents of the cloud of dust and gas from which the Sun and Solar System formed. The Earth lost its primordial atmosphere quite early, probably as a result of several processes, including irradiation from a young and very hot Sun and meteor showers.

But it is possible that an exoplanet similar to a super-Earth - more massive than Earth, but smaller than Neptune - will be able to retain its primordial atmosphere much longer than our planet did.

"Such massive primordial atmospheres can also induce a greenhouse effect - just like today's Earth's atmosphere," Helled explains.

To conduct this investigation, the team used simulations, modeling exoplanets with different nucleus masses, atmospheric masses, and orbital distances from their host stars, which the team modeled as similar to the Sun.

Their results showed that exoplanets with a dense primordial atmosphere could indeed be warm enough to maintain the presence of liquid water for up to 10 billion years.