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Nearby alien planets could be far more varied and unlike Earth than we realised, scientists say

Andrew Griffin
Tuesday 02 November 2021 16:05

Nearby exoplanets might be far more varied, and unlike Earth, than we had previously realised, according to scientists.

Some exoplanets might look markedly unlike anything not just on our planet but in our solar system, the researchers say.

When a star like our own Sun has used up its energy, it swells up to become a red giant and then shrink down again into a white dwarf. As it does so, it grabs nearby exoplanets, polluting the white dwarf with the rocky material it took from exoplanets.

In a new paper, published in the journal Nature Communications, researchers looked at the atmosphere of 23 of those nearby white dwarfs. They were able to explore the kinds of materials that were found in the stars.

Some had lots of calcium, but all had very little silicon, and high amounts of magnesium and iron. The authors suggest that those findings likely reflect the compositions of the exoplanets around those stars, before they were swallowed up.

When they compared those compositions with those of our Earth and other terrestrial planets in our solar system, they were vastly different.

As such, those exoplanets and the stellar systems that are their home could have a much wider variety of differently composed planets, made out of different kinds of rocks, than we had previously realised, the scientists say.

Researchers hope to examine why those other planets might be so different to our Earth, as well as looking at whether those differences happen by accident or are an inevitable result of the way that stars and planets form.

An article describing the research, ‘Polluted white dwarfs reveal exotic mantle rock types on exoplanets in our solar neighborhood’, is published in Nature Communications today.

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