Researchers have identified the type of exoplanets in which life may exist.
Earth is the only known inhabited planet. Therefore, in search of life on other planets, we focus on the parameters of our own. But the conditions for life as we know it may not be limited to Earth-like celestial bodies. Scientists have now been able to determine the type of exoplanets that could be inhabited for billions of years, according to Science Alert.
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The key parameter for the search is the presence of liquid water, which can exist for a long time. On Earth, liquid water was an important component of life. Exoplanets with water on them have a better chance of developing life as we know it.
Now a team of scientists led by Marit Mol Lus of the University of Zurich in Switzerland has concluded that a dense atmosphere of hydrogen and helium can maintain the temperature and conditions necessary for life to occur for a long time.
“One of the reasons that water on Earth can be liquid is its atmosphere. Due to its natural greenhouse effect, it captures exactly as much heat as is needed to create the right conditions for the oceans, rivers and rain, ”said astrophysicist-theorist Ravit Helled of the University of Zurich.
But the Earth's atmosphere has not always been as we know it today. Now most of it is nitrogen, followed by oxygen and only small amounts of hydrogen and helium. But when a planet is just forming, it is surrounded by a primary atmosphere, which consists mainly of hydrogen and helium, the main components of the cloud of gas and dust that formed the Sun and our system.
The Earth quickly lost its primary atmosphere probably due to several processes, including radiation from the young sun and meteorite bombardment. But it is likely that the alien exoplanet – more massive than Earth but less massive than Neptune – may retain its primary atmosphere for much longer.
“Such massive primary atmospheres can have a greenhouse effect – almost like today's Earth's atmosphere. So we wanted to find out if these atmospheres could help create the necessary conditions for liquid water, ”explains Helled.
The researchers simulated planets with different core masses, atmospheres, and different distances to stars. It turns out that planets with dense primary atmospheres can be warm enough to maintain the presence of liquid water for up to 10 billion years.
But there are some limitations. To avoid intense radiation, the planet must be at a sufficient distance from the star. About twice as far as the Earth is from the Sun. For the solar system, this is so far that any water must freeze.
The sun is not the only source of heat available to the planet. Some worlds, including the Earth, can generate their own heat. This can happen for a number of reasons, such as geothermal processes and the presence of radioactive elements that emit heat during decay.
and enough internal heat to warm up, the conditions for liquid water on the surface would be met, the researchers say.
This model of internal heat, hypothetically, could support life in worlds with a thick ice shell, such as Saturn's moon. Enceladus and satellite of Jupiter Europe. However, for the model of scientists it is necessary that several conditions were met in a particular place. According to scientists, this is not possible, but it may take a long time.
