Proxima Centauri, a small star 4.25 light-years from Earth, might be home to a third planet. Scientists discovered the latest finding using the European Southern Observatory.

Proxima d is its name, and its neighboring planets are Proxima b and Proxima c. The alleged closest star to Earth is a relatively bustling location, or so it seems. Astronomers have discovered the third planet around Proxima Centauri, bringing the total number of planets orbiting the star to three.

Researchers published the study, "A Candidate Short-Period Sub-Earth Orbiting Proxima Centauri," in Astronomy & Astrophysics.

An artist's interpretation of the exoplanet Proxima b

(Photo: ESO/M. Kornmesser)
This artist’s impression shows a view of the surface of the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to the Solar System. The double star Alpha Centauri AB also appears in the image to the upper-right of Proxima itself. Proxima b is a little more massive than the Earth and orbits in the habitable zone around Proxima Centauri, where the temperature is suitable for liquid water to exist on its surface.

Third Planet Found in Proxima Centauri Lighter Than Earth

According to Scientific American, Proxima d is thought to have just 25% of the mass of Earth, making it one of the lightest known exoplanets if verified.

Study lead author João Faria, a researcher at Portugal's Instituto de Astrofsica e Ciências do Espaço, said Earth's nearest star neighbor is filled with exciting new planets within reach of further study and potential exploration.

Proxima d completes one loop around Proxima Centauri every five Earth days. If Proxima d does exist, its orbit shows that it is too hot to support Earth-like surface life.

ESPRESSO (Echelle Spectrograph for Rocky Exoplanets and Stable Spectroscopic Observations), an instrument on the European Southern Observatory's (ESO) Very Large Telescope in Chile, was used to find Proxima d.

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Faria told Gizmodo that detecting Proxima d was a difficult task. According to the lead author, the team had difficulty analyzing the data.

It's fascinating to learn that it is now feasible to identify these low-mass planets, he added, which makes the researchers curious about future discoveries.

He was also surprised that the nearest star to the sun, of all the stars, was nevertheless "hiding" certain secrets.

Proxima d Found in the Habitable Zone

According to Republic World, Proxima d is in the "habitable zone" of the star, the precise range of orbital distances where liquid water may exist on a planet's surface.

Proxima Centauri also hosts Proxima b and c. Proxima b was discovered in 2016. Researchers revealed the discovery of a probable second planet in the system three years later, a candidate termed Proxima c that is at least six times the mass of Earth.

If Proxima c exists, it's likely too cold on its surface to support life as we know it; the hypothetical planet takes 5.2 years to complete one circuit around Proxima Centauri, which is considerably smaller and fainter than the sun.

Last year, TOLIMAN, a telescope devoted to hunting for possibly habitable planets orbiting the three Alpha Centauri stars, was revealed. However, Proxima d does not seem to fall under that crucial group.

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