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

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

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

To estimate the composition of this hypothetical planet – dubbed α-Cen-Earth – the team developed what it calls a devolatization model. To begin, they analyzed the amounts of volatile elements (hydrogen, carbon, oxygen, etc.) and non-volatile elements (like iron and silicon) in the Sun and Earth and looked at their differences.

Armed with this data, the team analyzed high-resolution spectroscopy data on the elements of the stars α Centauri A and α Centauri B – which yielded information on 22 elements. With their model and this data, they can estimate the probable compositions of a hypothetical rocky planet in the system’s habitable zone. “You get a model of the chemical makeup of rocky planets that would be in the habitable zone,” Charley Lineweaver, one of the paper’s authors, told Ars.

Show me what you’re made of

α-Cen-Earth, if present, is likely geochemically similar to Earth, with a likely silicate-dominated mantle. But it can hold more graphite and diamond, thanks to its higher carbon-to-oxygen ratio, according to Lineweaver.

The planet’s water storage capacity could also be similar to that of Earth’s core, but it would also have less geologic activity — perhaps without plate tectonics — and a smaller iron core. “The resulting planet will be interestingly different in terms of mineralogy and abundance of rocks compared to, for example, methane and carbides, graphite and maybe even diamond in the core,” Lineweaver said. .

According to Lineweaver, the model can also be applied to other hypothetical planets. He added that he personally 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 detecting them is somewhat limited.

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

Astrophysics Magazine, 2022. DOI: 10.3847/1538-4357/ac4e8c (About DOIs)

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