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Astronomie - Scientists discover third rock around alien sun

19.02.2022

The finding is a breakthrough in the way astronomers search for planets around distant stars, which could soon lead to the discoveries of even more worlds.

exoplaneten-1

An artist’s impression shows a close-up view of Proxima d, a planet candidate recently found orbiting the red dwarf star Proxima Centauri, the closest star to Earth's solar system.ESO / L. Calçada

Astronomers have found evidence of a third planet around the closest star to the sun, reinforcing the idea that planets are common around the stars of the galaxy, even some of its smallest.

And while the newly-found planet is less than half the size of Earth and probably too hot to be inhabited, there’s still a chance there could be life around Proxima Centauri, Earth’s nearest galactic neighbor.

 

“The planet is not within the star’s habitable zone — it’s orbiting too close,” said astronomer João Faria, the lead author of a study published this month in the journal Astronomy & Astrophysics that details the discovery. “So it’s unlikely that water can be in a liquid state and that the conditions are right for life.”

In fact, the new planet is so close — about a tenth of the distance between the sun and Mercury — that it takes just five days to complete an orbit around its star.

It’s also likely to be “tidally locked,” as the moon is to Earth, with one face always pointing toward Proxima Centauri. That could cause extremes of temperature and limits the likelihood that the planet has a stable atmosphere, Faria said.

But astronomers are excited by the discovery, despite the hostile conditions that could exist on the new planet.

Faria, a researcher at the Institute of Astrophysics and Space Sciences at the University of Porto in Portugal, said it suggests the Proxima system could be “packed with planets.”

It’s also a breakthrough in the way astronomers search for planets around distant stars, which could soon lead to the discovery of even more, he said in an email.

The new planet will have to be verified by other observations, but Faria and his co-authors say they detected it in tiny variations in Proxima’s starlight “wobbles” caused by the planet’s gravity.

Similar techniques were used to detect the first planet found around Proxima in 2016, and a second planet in 2019.

But the latest search used light gathered by a new spectrograph at the Very Large Telescope on a mountaintop in the Atacama Desert of northern Chile — a more sensitive instrument than used before.

 

NASA’s James Webb space telescope to travel 1 million miles from Earth 

“We are now able, in terms of instrumental precision, to detect such small signals, which opens the possibility of finding planets like the Earth around stars like the sun in the not-so-distant future,” Faria said.

Proxima Centauri is the third star of the Alpha Centauri system, which looks like a single bright star from Earth.

It’s just over four light-years away, or about 25 trillion miles — but despite that vast distance, it’s the closest star system.

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