What would an Earth-like planet look like in Alpha Centauri?

Zoom / Artist’s impression of an Earth-like planet in a nearby star system.

We now know that our closest neighbor, Proxima Centauri, is It hosts at least two planets. But we’re not sure if there are any planets near Alpha Centauri, a binary system just beyond that. However, if they were there, we now know what they could look like. new search Use modeling data and spectroscopy of the system’s stars to estimate what a rocky planet might have formed in the system’s habitable zone.

To estimate the composition of this hypothetical planet – nicknamed α-Cen-Earth – the team developed what they call a devolatization model. To start, they looked at the amounts of volatile elements (hydrogen, carbon, oxygen, etc.) and non-volatile elements (such as iron and silicon) in the sun and Earth, and examined how they differed.

Armed with this data, the team then looked at high-resolution spectroscopy data on the elements in the α Centauri A and α Centauri B stars — which provided them with information about 22 elements. With their model and these data, they can estimate the likely compositions of a hypothetical rocky planet in the system’s habitable zone. “You get a model of the chemical composition of the rocky planets that would be in the habitable zone,” Charley Lineweaver, one of the authors of the paper, told Ars.

Show me what you’re made of

α-Cen-Earth, if present, is likely to be geochemically similar to Earth, with a mantle likely dominated by silicates. But it may contain more graphite and diamond, thanks to its higher carbon-to-oxygen ratio, according to Lineweaver.

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The planet’s water storage capacity might also be similar to Earth’s core, but it would also have lower geological activity—perhaps lacking plate tectonics altogether—and a smaller iron core. “The planet that results will be interestingly different in terms of mineralogy and rock abundance versus, say, methane and carbides, graphite, and possibly even diamond in the core,” Lineweaver said.

According to Lineweaver, the model can also be applied to other hypothetical planets. He added that, personally, he suspects that rocky planets are more common in other solar systems than we’ve discovered so far — not that they don’t exist, it’s just that our ability to detect them is somewhat limited.

It is possible, however, that α-Cen-Earth – or any other planet – might differ from the model because meteorites bearing other elements often collide with planets, which could affect their overall chemical composition. However, the team’s model could help future researchers identify habitable planets, Lineweaver said.

Astrophysical Journal, 2022. DOI: 10.3847 / 1538-4357 / ac4e8c (About DOIs)

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