The planet is not habitable, it is too close to Alpha Centauri B. But rocky planets tend to have siblings, researchers note, raising hopes others could be found in the system just 4.4 light-years distant.
L. Calcada/N. Risinger/ESO/Reuters
Astronomers have discovered a rocky, Earth-mass planet right in our own sun’s galactic neighborhood. The planet is orbiting a star a mere 4.4 light-years away in the multiple-star Alpha Centauri system, which may well turn out to be a cosmic condo, hosting additional planets.
A habitable planet could well be among them, some astronomers speculate.
The planet, with an estimated mass 1.13 times higher than Earth's, is orbiting Alpha Centauri B, which forms a binary pair with Alpha Centauri A. Both essentially share the sun's mass and are only slightly older than the sun. The system includes a smaller, dimmer star called Proxima Centauri.
With a "year" that corresponds to 3.2 Earth days, the newfound planet is too close to the star to be habitable, notes Xavier Dumusque, a PhD student in astrophysics at the University of Porto in Portugal. He led the team reporting the discovery in Thursday's issue of the journal Nature.
The planet is gravitationally bound to the star in such a way that it presents the same face to Alpha Centauri B all the time. This sets up temperatures on the day side that could top 2,200 degrees Fahrenheit, melting rock – a sharp contrast with the night side, perpetually facing the cold of space.
Still, researchers point out that rocky planets tend to have siblings.
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