US, WASHINGTON (ORDO NEWS) — The number of exoplanets with oceans can be much higher than previously thought. Calculations showed that every fourth in the exoplanet galaxy boasts this distinctive property.
Inside the solar system there are several bodies on which scientists do not exclude the existence of primitive life forms in the present or in the past. Among them are Mars, Ceres, Callisto, Europe, Ganymede, Enceladus, Titan, but they may also include Dion, Mimas, Triton and the dwarf planet Pluto.
On these bodies, at present or with a high probability in the past, there existed liquid oceans containing large volumes of liquid water, as well as organic molecules, and tidal heating, which, according to scientists, are necessary for life .
All this leads scientists to a reasonable question – are there many similar bodies with oceans in other stars?
Lynna Quick and her colleagues from the Goddard Space Center (NASA) tried to answer it. In their study, published in the journal Publications of the Astronomical Society of the Pacific, analyzed samples of already known planetary systems, and concluded that planets with oceans are a common occurrence in our galaxy.
To find out, scientists tried to estimate how many of the exoplanets have geological activity. The fact is that similar activity, accompanied by emissions of matter, is likely to be able to fix telescopes of future generations.
“There are emissions of water on Europe and Enceladus, so we can say that under the ice crust of these bodies there are oceans and they have enough energy to support these emissions. Therefore, if we think of these places as possibly inhabited, possibly larger versions of them in other planetary systems are inhabited too,” said Quick.
Scientists chose 53 exoplanets known to science that are no larger than 2 Earth radii in size and no more than 8 Earth masses in mass and estimated how much heat such planets can release. An example of the solar system says that there are two sources of own heat – the decay of radioactive elements in the crust and mantle, and tidal effects from other bodies. In the case of the Earth, decay energy is released in the form of volcanism and tectonic movements. On satellites such as Europe, Enceladus, Triton, cryovolcanism and the movement of the ice crust are observed.
Calculations showed that over a quarter of the selected exoplanets (26%, or 14 of 53) are more likely to have oceans, and the energy release of most of them exceeds the energy release of Europe or Enceladus.
Knowledge of the planet’s energy release is extremely important when evaluating its possible habitability. For example, too active volcanic activity can turn the surface into a lifeless desert, the gases emitted at the same time – poison the entire atmosphere. Too weak activity, on the contrary, can lead to the absence of greenhouse gases in the thin atmosphere.
In addition, scientists examined the famous planetary system TRAPPIST-1, consisting of seven solid planets, three in the habitable zone. According to Quick’s calculations, the four planets of this system – e, f, g and h can have oceans. According to scientists, the study has many assumptions, but the estimates obtained may indicate what goals to pay attention to when studying with new telescopes. One of them will be the long awaited James Webb Space Telescope.
“Future missions to search for life outside the solar system focus on planets like ours, which have a global biosphere so large that it changes the chemistry of the entire atmosphere,” explained Aki Roberge, co-author of the study. “However, in the solar system, icy satellites with oceans located far from solar heat also demonstrate properties that we think are necessary for life.”
Recently, British scientists tried to find out how many intelligent civilizations can exist in the Milky Way galaxy. After making new estimates on the example of the Earth, they came to the conclusion that this number can be a little over three dozen. They conducted a new assessment, suggesting that different civilizations in different parts of the galaxy require approximately the same time for development, and concluded that there may be 36 of them in our Milky Way galaxy.
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