According to one study published on June 27 by researchers at the University of Zurich, the Super-Earths could accommodate life for several tens of billions of years. 84 billion years to be exact.
Super-Earths: the new fad of astronomers?
Super-Earths, which are rocky planets more massive than Earth but smaller than ice giants such as Neptune, are abundant in the star systems of the Milky Way. Our own solar system might even be an exception due to the absence of this type of planet. A team of scientists led by Marit Mol Lous, a PhD student studying exoplanets at the University of Zurich, has shown that cold Super-Earths, which are more than twice the distance from their star the Earth and the Sun, “can sustain temperate surface conditions for billions of years”.
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Concretely, this study suggests that the concept of planetary habitability could be reviewed and made more “trivial” than what we thought. Additionally, Mol Lous and his colleagues discovered that some Super-Earths that are ejected from their home star system by gravitational disturbances or other mechanisms, could potentially maintain liquid water habitats for 84 billion years. These “rebellious planets” would not be affected by the death of their host star. According to Marit Mol Lous, “Our research shows that habitable planets could be very different from Earth, and that we need to keep an open mind when studying such potentially habitable planets”.
Liquid water: the essential element of life
The study was conducted from theoretical models on Super-Earths, rather than actual observations, because it is difficult to spot these Super-Earths with the telescopes we currently have. Most exoplanets are detected when they pass in front of their star relative to our perspective on Earth, causing the starlight to dim slightly. Scientists have suspected for years that super-Earths in more distant orbits could be attractive targets in the search for extraterrestrial life. Models suggest that these planets could preserve their atmospheredominated by hydrogen and helium gases, for billions of years.
These atmospheres are different from those around some rocky planets in our own solar system, including Earth, which have evolved into atmospheres containing more complex compounds, such as oxygen, carbon dioxide and nitrogen gas. Marit Mol Lous believes that “we calculated how long liquid water could be present on this kind of planet”. Indeed, liquid water is the magic ingredient of life as we know it on Earth, which is why scientists focus on this element in the search for extraterrestrial life elsewhere in the universe. Mol Lous and his colleagues have performed more than 1,000 simulations of planets of different masses, atmospheres and orbital distances.
The team found that planets with masses between one and ten times that of Earth, and whose atmospheres are 100 to 1,000 times thicker than Earth’s, could occupy a privileged position in terms of habitability.