Denis Villeneuve's sci-fi masterpiece Dune: Part 2 The film hits theaters in the US in spring 2024. The movie follows the power struggles of the noble families of the desert planet Arrakis. But what if humanity had become an empire that spanned thousands of worlds in the distant future, as depicted in the film? Sand Dunes How common are desert planets or planets with no water at all in movies and novels?
In the search for these planets, a good place to start is with the most common stars: astronomers have observed what are called small, faint, cool, reddish stars. Red dwarf They make up most of the stars in the galaxy. Astronomers who study planets around stars other than the Sun estimate that every star has at least one planet. About half of the planets around red dwarfs are small, rocky planets with compositions similar to Earth. On the ground planet. Therefore, the most common type of terrestrial planet is thought to be around a red dwarf star.
For decades, astronomers have thought that red dwarfs are too cold for liquid water to exist on their surfaces. To reach the temperature range needed to support liquid water, planets around cooler stars need to orbit closer to their host stars than planets around hotter ones. But unlike stars like the Sun, which have a constant brightness, red dwarfs are born hotter and brighter than their final state for most of their lives.
The terrestrial planets formed with 15 to 70 times more water than Earth, most of it coming from drifting icy comets. But the heat of the young red dwarf star causes the water on these planets to evaporate, turning from liquid to gas in their atmospheres. In the planet's atmosphere, the intense starlight breaks down the water vapor into oxygen and hydrogen. Photolysis. The heavier oxygen stays on the planet while the lighter hydrogen drifts away, and astronomers estimate that as a result, planets around red dwarf stars lose tens of times as much water as Earth's oceans over their first billion years.
A team of Japanese scientists led by Hiroshi Kawamura challenged the paradigm that planets around red dwarfs should lose all their water in this way. They proposed that two factors could significantly reduce the initial water loss of planets orbiting dwarf stars. First, water is decomposed by the intense light in the planet's atmosphere, but some water is produced in the atmosphere when reactive free hydrogen mixes with hydrogen superoxide. Second, the decomposition of water in the atmosphere produces oxygen gas, which protects the water from further intense light.
Kawamura's team used software called the Photochemical and Radiation Transport Model to Proteus To test whether the planet would lose less water if these two factors were taken into account. The researchers calculated the water loss for an Earth-like planet with a water vapor-filled atmosphere and huge oceans. The planet orbits the dwarf star at a distance about 2% of the distance it orbits around the Sun, relative to TRAPPIST-1, shown in the featured image above. The researchers assumed that the only chemical reaction occurring in the planet's atmosphere is between hydrogen and oxygen. Kawamura and his team ran the model once to see if the results differed from previous studies and how they changed depending on the altitude of the planet's atmosphere.
The team found that the model planet's atmosphere turned out as expected: It had a very high layer of atmosphere, where starlight split water into free hydrogen and oxygen atoms, with the hydrogen escaping into space, and a layer of oxygen gas formed below, reducing the intensity of the starlight at lower altitudes, and the free hydrogen mixed with hydrogen superoxide in a chemical reaction to produce more water.
Ultimately, they calculated that the amount of water lost to space was only about seven times that of Earth's oceans. This means that even if a terrestrial planet started at the low end of the water content range, it could still have eight times as much water as Earth's oceans after its first billion years of existence. The researchers suggested that their findings imply that rather than a galaxy filled with planets with little water, like Earth, the universe could contain worlds with vast oceans orbiting dwarf stars. In other words, future humans are likely to discover Arrakis, but not Caladan. Still, they suggested that future researchers should test planetary water loss models with different atmospheric compositions, alternative cooling processes, and water trapped in the planet's rocks and magma.
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Source: sciworthy.com
