Europan Space Whales Somebody? Planets that fall under Deep Oceans can still have life on them

In recent decades, astronomers have discovered many planets that they believe to be "earth-like" in nature, which means that they resemble the Earth's surface (ie rocky) and their stars rotate at the right distance for the existence of liquids. water on their surface. Unfortunately, recent research has shown that many of these planets in fact & # 39; water worlds & # 39; can be where water forms a significant part of the planet's mass.

For the scientific community, this seemed to indicate that these worlds could not be inhabited for long because they would not be able to support the cycling of minerals and gases that would keep the climate on earth stable. According to a new study by a team of researchers from the University of Chicago and the Pennsylvania State University, these "water worlds & # 39; however, are better habitable than we think.

Their study, entitled "Habitability of exoplanet waterworlds", recently appeared The Astrophysical Journal. The study was conducted by Edwin S. Kite, assistant professor at the department of geophysical sciences at the University of Chicago; and Eric B. Ford, a professor at the Center for Exoplanets and Habitable Worlds at Pennsylvania State University, Institute for CyberScience and the Pennsylvania Astrobiology Research Center.

Artist & # 39; s image of a water world. A new study suggests that the earth is in a minority when it comes to planets, and that most habitable planets can be greater than 90% ocean. Source: David A. Aguilar (CfA)

Artist & # 39; s image of a water world. A new study suggests that the earth is in a minority when it comes to planets, and that most habitable planets can be greater than 90% ocean. Source: David A. Aguilar (CfA)

For their studies, Vlieger and Ford constructed models for rocky planets that had many times the water of the Earth, taking into account how the temperature and chemistry of the ocean would evolve over a period of several billions. The aim was to address a number of long-term assumptions when it comes to planetary habitability. The most important is that planets must have the same conditions as the earth to sustain life for long periods.

For example, Planet Earth has been able to maintain stable temperatures over long time scales by removing greenhouse gases in minerals (leading to global cooling) and warming themselves by releasing greenhouse gases via volcanoes. Such a process would not be possible on water worlds, where the entire surface (and even a significant mass fraction) of the planet consists of water.

On these worlds, water would prevent the absorption of carbon dioxide by rocks and suppress volcanic activity. To tackle this, Kite and Ford have set up a simulation with thousands of randomly generated planets and track the evolution of their climates over time. What they discovered was that water worlds would still be able to maintain a temperature equilibrium for billions of years. As Kite explained in a recent press release from UChicago News:

"This really pushes back against the idea that you need an Earth clone, that is, a planet with some land and a shallow ocean … The surprise was that many of them remain stable for over a billion years, just by the luck of the draw.Our best estimate is that it is in the order of 10 percent of them. "

Artist's impression of what an Earth-like exoplanet might look like. Credit: ESO

For these planets, which are just the right distance from their stars, the simulations indicated that the right amount of carbon was present. And although they did not have enough minerals and crude elements dissolved in the oceans to extract carbon from the atmosphere, they had enough water to circulate carbon between the atmosphere and the ocean. Apparently, this process was enough to keep the climate stable for several billion years.

"How much time a planet has is basically dependent on carbon dioxide and how it is distributed in the early years between the ocean, the atmosphere and the rocks," said Kite. "It seems that there is a way to keep a planet habitable for a long time without the geochemical bikes we see on Earth."

The simulations were based on planets in orbit around stars like our own G-type (yellow dwarf) stars – but the results were also optimistic for M-type (red dwarf) stars. In recent years, astronomers have found that these systems are promising for advancing life because of their natural lifespan and how they gradually become clearer over time – making life take much longer to emerge.

Although red dwarfs are also known as variable and unstable compared to our sun, resulting in countless torches that can strip the atmosphere of a planet, the fact that an ocean world would be able to circulate enough carbon to circulate to keep the atmosphere at a constant temperature encouraging. Assuming that some of the planets in a orbit of red dwarfs have a protective magnetosphere, they too would be able to maintain life-threatening conditions for extended periods of time.

Artist impression of Proxima b, which was discovered using the Radial Velocity method. Credit: ESO / M. Kornmesser

In recent years, the wave of exoplanet discoveries has caused the focus of exoplanet research to shift from detection to characterization. This in turn led scientists to speculate about the types of circumstances under which life could emerge and thrive. Although the low-hanging fruit approach is still the most important tool used by scientists to find potentially habitable planets – where scientists search for planets that have the same conditions as the Earth – it is clear that there are other possibilities.

In the coming years, with the deployment of space-based telescopes such as the James Webb Space Telescope (JWST) and ground-based telescopes such as the Thirty Meter Telescope, the Extremely Large Telescope and the Giant Magellan Telescope, astronomers will be able to characterize the atmospheres of exoplanets and determine whether they are indeed water worlds or planets with continental crusts (such as Earth) ).

Using the same telescopes, astronomers can also search for biosignatures in these spheres, which will not only help determine whether they are "habitable" but "potentially occupied".

Read more: UChicago News

Matt Williams is the guide to space of the curator of the universe. He is also a freelance writer, a science fiction author and a Taekwon-Do instructor. He lives with his family on Vancouver Island in beautiful British Columbia.

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