Feb 11, 2021 - Science

A nearby star may have a planet orbiting in its habitable zone

Two bright twin stars shine, with rays shooting out of them against the blackness of space

Alpha Centauri A (L) and Alpha Centauri B seen by the Hubble Space Telescope. Photo: NASA/ESA

A planet about the size of Neptune could be lurking in the habitable zone of one of our nearest stars, Alpha Centauri A, according to a new study.

Why it matters: It's an exciting hint that potentially habitable alien worlds could be just a few light-years away.

What they found: The possible planet was discovered using about 100 hours of telescope time that allowed scientists to directly image the habitable zones — the orbits around a star where water could exist on a planet's surface — of the two Sun-like stars in the Alpha Centauri system.

  • The system is only 4.37 light-years from Earth, and this marks the first time the habitable zones of Alpha Centauri A and Alpha Centauri B have been directly imaged.
  • Until now, habitable zone planets had not been found around either of those stars, but another star in the system, Proxima Centauri — a red dwarf star smaller than the Sun — appears to host to a possible planet in its habitable zone.
“We were amazed to find a signal in our data. While the detection meets every criteria for what a planet would look like, alternative explanations – such as dust orbiting within in the habitable zone or simply an instrumental artifact of unknown origin – have to be ruled out.”
— Kevin Wagner, an author of the new study in Nature Communications, said in a statement

The big picture: Scientists usually find planets by detecting the small dips in a star's light created when a world passes in front of its star from Earth's perspective.

  • Researchers are also able to detect the tiny wobbles of a star created by the slight tug of a planet's gravity as it orbits.
  • Direct imaging, on the other hand, allows astronomers to potentially learn more about a planet's atmosphere, composition and size.
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