Science and Tech

Conditions suitable for life on a class of planets very different from Earth?

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It has been believed that the most plausible scenario for the emergence of life is that offered by rocky planets like Earth, with continents and seas under an atmosphere that has evolved a lot from the typical primitive composition of hydrogen and helium. However, new research has concluded that another class of planets, very different, can also offer conditions suitable for life, and also with great stability that would allow such conditions to be maintained for billions of years. years.

Planets with a primordial atmosphere of hydrogen and helium could have the temperatures and pressures that allow the existence of liquid water, a key ingredient for life.

The team of Christoph Mordasini, professor of theoretical astrophysics at the University of Bern in Switzerland, has concluded that super-Earths (rocky planets like Earth but of greater mass) with masses between 1 and 10 times that of Earth could maintain habitable conditions at distances from their star at which typical rocky planets, with evolved atmospheres, would be icy and incapable of supporting life. In addition, these conditions of habitability in such super-earths with an atmosphere of hydrogen and oxygen could be preserved for a long period of time, specifically between 5,000 million and 8,000 million years.

The higher temperature than normal would be reached basically thanks to a mechanism of absorption of infrared light by hydrogen, whose action intensifies with pressure. The higher the pressure, the hotter.

The research team took into account not only the properties of the planets’ atmospheres, but also the intensity of radiation from their respective stars, as well as the internal heat of the planets that tends to emanate outwards. While on Earth, this geothermal heat plays only a minor role in setting conditions at the surface and nearer the surface, it can contribute more significantly on planets with massive primordial atmospheres.

Super-Earths with an atmosphere of hydrogen and helium could have the temperatures and pressures that allow liquid-phase water, even at great distances from their star. The presence of liquid water is favorable for life, so these planets could harbor exotic habitats for billions of years. (Image: Thibaut Roger / Universität Bern / Universität Zürich. CC BY-NC-SA)

The results of the study significantly expand the horizon of the search for extraterrestrial life in the cosmos.

“For many, this may come as a surprise. Astronomers usually expect liquid water to exist on worlds in orbital fringes around their star that receive just the right amount of radiation: not too much so that the water doesn’t evaporate, not too much little, so it doesn’t all freeze,” emphasizes Mordasini.

Now, on the other hand, taking into account the results of the study, it is worth considering that there may be life on planets very far from their stars. Mordasini thinks there might even be it on planets without a star. These are worlds that float in interstellar space unaccompanied by host suns or companion planets, and whose orbital path can only be around the center of the galaxy. Until a few years ago, it was believed practically impossible that there could be planets without a star. However, recently the belief that such planets are tremendously abundant in the cosmos is gaining more and more strength.

The study is titled “Potential long-term habitable conditions on planets with primordial H–He atmospheres.” And it has been published in the academic journal Nature Astronomy. (Font: NCYT by Amazings)

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