Next b: Comet water?



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The red dwarf Proxima Centauri is only four light-years away from us and has a planet in the habitable zone as astronomers discovered in 2016. The planet roughly the size of Earth and potentially life-friend could not only be a valid target for a first interstellar mission, but could also give him an extraterrestrial life. However, this assumes that there is also liquid water in the earth twin.

Refueling should come

But how likely is the presence of water in Proxima Centauri b? Although the earth's twin temperatures are mild enough to allow this. But as its central star tends to frequent outbreaks, strong stellar winds can evaporate the existing water again and again and blow into space.

But that means: to permanently preserve the oceans and other waters of the planet, the planet's water supply would have to be replenished repeatedly, for example, by the impacts of water-rich comets. In fact, images of the Proxima Centauri system show that the star is surrounded by several dust belts that may contain pieces up to 50 kilometers in size.

Dust Belt Comets

If these dust belts could serve as a supplier of water to the earth twin, Proxima b was now determined by Richard Schwarz of the University of Vienna and his colleagues. For their study, they modeled the system on a physical computer model and investigated whether and how the dust belt comets could be directed to the planet, how often it hit, and how much water it would produce.

The result: Both the influence of the gravity of the adjacent double star of Alpha Centauri and the existence of a possible second planet around Proxima Centauri could always drive out ice-rich chunks of the belts. They run through the system like comets, crossing the path of the Earth's twins, so the impact of such chunks would be quite likely, astronomers said.

30 oceans of land filled with water

This means that: Throughout its long history, the Earth Proxima b twin could be receiving water through impacts of ice-rich comets. "Our simulations indicate that a potential water transport from an area rich in comets near the planet is more effective," says Schwarz. Especially the dust belt, which wraps the star in one to four astronomical units away, would be an obvious source of comets.

How much water the planet receives Proxima Centauri b for such impacts, the researchers also determined. "We were able to show that the comet's impacts on Proxima Centauri over a two-million-year period can provide a mass of up to 30 terrestrial oceans of water," says Schwarz. Including extremely close approaches and intersections in the simulations, comets could bring even more water to the planet.

The fact that our nearest neighbor is a "second earth" with oceans of liquid water, however, will have to be confirmed by future observations. But the models of Schwarz and his team show at least one way in which the Earth's twin could have enough water. (Monthly Notices of the Royal Astronomical Society, 2018; doi: 10.1093 / mnras / sty2064)

This article was written by NPO

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