Astronomers have found evidence for a new planet circling Proxima Centauri, the nearest star to the sun.

The alien world is only a quarter of the mᴀss of Earth and orbits extremely close to its parent star, at one tenth of the distance between the sun and Mercury, the solar system’s innermost planet.

Updated version of the previous article.

Researchers discovered the new planet by examining minor wobbles in Proxima Centauri’s velocity caused by the gravitational pull it exerts as it swings around the star. Observations with the European Southern Observatory’s Very Large Telescope (VLT) in Chile indicate that the planet orbits the star once every five days.

The discovery demonstrates that our nearest stellar neighbour is “filled with exciting new worlds” that can be studied further and explored in the future, according to Joo Faria, a researcher at the Insтιтute of Astrophysics and Space Sciences in Portugal and the study’s primary author.

Scientists believe the planet orbits Proxima Centauri around 2.4 million miles (4 million kilometres), putting it closer to the star than its habitable zone, where the temperature range is just right for water to run freely. The findings have been published in the journal Astronomy & Astrophysics.

The planet, known as Proxima d, is the third – and lightest – to be discovered in the vicinity of Proxima Centauri, the closest star to the solar system at four light years away. It joins Proxima b, a planet with a mᴀss equal to Earth that orbits the star every 11 days, and Proxima c, which takes around five years to circle the star.

The first indications of the planet were in 2020, when astronomers observed Proxima Centauri in order to prove the presence of Proxima b. The observations indicated a modest signal in the star’s motion that was consistent with a planet orbiting every five days.

Further studies with the Espresso instrument on ESO’s telescope verified researchers’ concerns that the cause was a planet rather than changes in the star itself.

“This is a very low mᴀss planet, and is the third candidate around the star closest to us,” Faria said. “It shows that these planets, similar to the Earth, may be common in our galaxy, and just close by. And it makes us wonder about the possible conditions for habitability in these planet systems and if it’s possible for life to appear in other places in the universe.”

Source: Astronomy & Astrophysics