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Possible planet is spotted around sunlike Alpha Centauri star

An artist’s rendering provided by NASA of the gas giant orbiting Alpha Centauri A (upper left). Astronomers have found strong evidence that a gassy Jupiter-size world is orbiting Alpha Centauri A, one of three stars in the solar system closest to our own. (NASA via The New York Times)
By Katrina Miller New York Times

A team of astronomers on Thursday provided the strongest evidence yet that a planet circles one of Alpha Centauri’s sunlike stars. The world is at the very edge of the region around the star where liquid water can exist, known as the habitable zone.

Because it is made of gas, the planet itself would not support life as we know it. But the possible planet, discovered through observations from NASA’s James Webb Space Telescope, would be the closest ever found orbiting within a sun-like star’s habitable zone. However, further observations are needed to confirm it is indeed a planet.

The find was announced in two papers that have been accepted for publication in the Astrophysical Journal Letters. It is a potential preview of the types of discoveries that will be possible in the future as astronomers’ tools for hunting exoplanets – particularly ones like Earth – evolve.

Three stars make up Alpha Centauri. But only two, Alpha Centauri A and Alpha Centauri B, are like our sun. They are locked in close orbit around each other. Circling this pair from farther away is a faint red dwarf known as Proxima Centauri.

The stars themselves are “pretty run-of-the mill,” said Charles Beichman, an astronomer at NASA’s Jet Propulsion Laboratory and the California Institute of Technology. But the system is a touchstone for investigations of stars like our sun, Beichman added, because cosmically speaking, “it’s right next door.”

The planet, if it is one, is about the size of Jupiter and has about the mass of Saturn. It orbits Alpha Centauri A every two Earth-years at roughly one to two times the distance between our sun and Earth. It has a temperature of about minus 55 degrees Fahrenheit.

To claim a discovery, astronomers will need to find the planet again, either with the Webb telescope, with another observatory on the ground or in space. The Extremely Large Telescope, a European observatory under construction in Chile, could help. So could NASA’s Roman Space Telescope, scheduled to launch by May 2027.

This article originally appeared in The New York Times.