Astronomers have found evidence of a third planet around the star closest to the sun, reinforcing the idea that planets are common around galactic stars, even some. its smallest.
And while the newly found planet is less than half the size of Earth and may be too hot to be habitable, there is still the possibility of life around Proxima Centauri, Earth’s nearest galactic neighbor. .
“The planet is not in the habitable zone of the star – it orbits too close,” said astronomer João Faria, lead author of the study. published this month in the journal Astronomy & Astrophysics details the discovery. “So it’s unlikely that water could be liquid and have the right conditions for life.”
In fact, the new planet is so close – one-tenth of the distance between the sun and Mercury – that it takes only 5 days to complete one orbit around its star.
It is also likely to be “locked in order”, as the moon is with the Earth, with one side always facing Proxima Centauri. That could cause extreme temperatures and limit the planet’s ability to have a stable atmosphere, Faria said.
But astronomers are excited by the discovery, despite the hostile conditions that may exist on the new planet.
Faria, a researcher at the Institute of Astrophysics and Space Sciences at the University of Porto in Portugal, said they think the Proxima system could be “filled with planets.”
It’s also a breakthrough in how astronomers search for planets around distant stars, which could soon lead to even more discoveries, he said in an email.
The new planet will have to be verified with other observations, but Faria and his co-authors say they detected it in small variations in Proxima’s starlight – “wobble” caused by the planet’s gravity.
Similar techniques were used to detect the first planet found around Proxima in 2016 and the second in 2019.
But the latest search used light gathered by new spectrometer at the Very Large Telescope atop a mountain in the Atacama desert of northern Chile – a more sensitive device used before.
“We are now able to detect such small signals which, in terms of instrument accuracy, can detect such small signals, which opens up the possibility of finding planets,” said Faria. like the Earth around stars like the sun in the not-so-distant future.”
Proxima Centauri is the third star of the Alpha Centauri system, which looks like a single bright star from Earth.
It is just over four light-years away, or about 25 trillion miles — but despite that vast distance, it is the closest star system.
Only the light from its two brightest stars, Alpha Centauri A and Alpha Centauri B, can be seen with the naked eye.
They orbit each other, but are far enough apart that they are said to not interfere with each other’s planets.
And because Alpha Centauri A and B are both very similar to the sun, it’s possible that life could have evolved on their planets or moons – so scientists plan to look for them with a probe. dedicated space telescope.
On the other hand, Proxima Centauri is a small and very faint red dwarf discovered by the telescope in 1915, very far away from the system’s two main stars.
Technically, Proxima was the closest star to the sun – about a trillion miles closer than other stars – until its orbit took it further away in about 25,000 years (its name comes from the word Latin for “closest”).
Unlike Alpha Centauri A and B, where no planets have been verified, three planets have now been discovered around Proxima.
However, none of them are thought to be very similar to Earth, because Proxima is an active “flare star” that regularly dosed its planets with intense bursts of radiation. high.
But it’s still possible that life may have evolved on at least one of its planets, said Guillem Anglada-Escudé, an astronomer at the Institute of Space Sciences in Barcelona, Spain. .
He led the announced group Proxima’s First Planet in 2016. That planet was found to be about the size of Earth and lies within Proxima’s narrow “Goldilocks” zone, where it is neither too hot nor too cold – “just right” – for the giants water on its surface.
Current observations suggest that there may indeed be oceans there; and if so, they could replenish atmospheric gases removed by Proxima’s frequent fires, he said. The oceans can also act as a barrier to flares, and so it’s possible marine life evolved.
Anglada-Escudé hopes more planets will be found around Proxima Centauri and other stars as astronomical instruments and techniques improve.
“Within a decade, we should be able to detect these planets directly,” he said. “The idea would be to look for life, to see from the spectrum of a planet if there are chemicals that can’t be explained by other natural processes.”
