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The solar system closest to ours may actually host two potentially vital planets, according to a new study.
In 2016, scientists discovered a world about the size of Earth encircling Proxima Centauri, part of the three stars Alpha Centauri System, which is about 4.37 light years from Earth. The planet, known as Proxima b, orbits in the “habitable zone,” the range of distances from a star at which liquid water could exist on the surface of a world. (A second planet, Next c, was later discovered encircling the star as well, but it orbits further beyond the outer limits of the habitable zone.)
There is considerable debate about the true livability of Proxima b, however, since its parent star is a red dwarf. These stars, the most common in the Milky Way, are small and dark, so their habitable zones lie very close – so close, in fact, that the planets that reside there tend to be locked, always showing the same face. to their host stars. , just as the moon always shows the Earth its near side. Additionally, red dwarfs are prolific flarers, especially when they are young, so it’s unclear whether their habitable zone worlds can retain their atmosphere for a long time.
Proxima B: the closest discovery of an Earth-like planet in pictures
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The other two stars of the Alpha Centauri trio, however, resemble the sun – a pair called Alpha Centauri A and B, which together form a binary orbiting the same center of mass. And Alpha Centauri A could have its own habitable zone planet, according to the new study, published online today (February 10) in the journal Nature Communications.
The study presents the results of Near Earth in the Alpha Cen region (NEAR), a $ 3 million project led by the European Southern Observatory (ESO) and Breakthrough Watch, a program that searches for potentially Earth-like worlds around nearby stars.
NEAR searched for planets in the habitable zones of Alpha Cen A and B using ESO Very large telescope (VLT) in Chile. The NEAR team improved the VLT with several new technologies, including a thermal coronograph, an instrument designed to block light from a star and help pinpoint thermal signatures of orbiting planets.
After analyzing 100 hours of data collected by NEAR in May and June 2019, scientists detected a thermal footprint in the living area of Alpha Centauri A. The signal potentially corresponds to a world the size of Neptune orbiting between 1 and The star’s 2 astronomical units (AU), study team members said. (One AU, the average Earth-Sun distance, is about 93 million miles, or 150 million kilometers.)
But this planet has not yet been confirmed, so it remains a candidate for now.
“We were amazed to find a signal in our data. While the detection meets all the criteria for what a planet would look like, alternative explanations – such as dust orbiting the habitable zone or simply an instrumental artifact of unknown origin – must be, ”the author said. Study principal Kevin Wagner, Sagan fellow of NASA’s Hubble Fellowship program at the University of Arizona, in a statement.
“Verification can take some time and will require the involvement and ingenuity of the scientific community as a whole,” Wagner added.
Study co-author Pete Klupar said he hopes the new findings will prompt astronomers to study the Alpha Centauri system in more detail, both through new observational programs and further examination. archived data, which may contain unrecognized evidence of the exoplanet candidate.
“It’s like having a clue [the board game] Clue, “Klupar, a researcher from the parent organization of Breakthrough Watch, Breakthrough initiatives, Space.com said. “Now that we have the clue, maybe they can find something.”
And, if the Alpha Centauri A world does exist, it might not be alone.
“In my mind, the most exciting thing about it is that once we find one planet, we tend to find others,” Klupar said.
Even if planet Alpha Cen A turns out to be a mirage, NEAR’s work will not have been in vain, team members said.
“The new ability we have demonstrated with NEAR to directly image nearby habitable zone planets is a source of inspiration for further developments in exoplanet science and astrobiology,” Wagner said in the same release. .
Mike Wall is the author of “Over there“(Grand Central Publishing, 2018; illustrated by Karl Tate), a book on the search for extraterrestrial life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook.
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