Using the European Southern Observatory’s Very Large Telescope (ESO’s VLT) in Chile, a team of astronomers have discovered evidence of another planet orbiting Proxima Centauri.
Proxima Centauri is the closest star to our solar system. This candidate planet is the third discovery in the system and the lightest planet discovered so far orbiting this star.
The explored planet is only a quarter the mass of Earth and is one of the lightest exoplanets ever found, according to João Faria, a researcher at the Instituto de Astrofísica e Ciências do Espaço in Portugal, and lead author of the study, which was recently published in the journal Astronomy & Astrophysics.
Proxima Centauri, the closest star to the Sun, is located just over four light-years away, according to scientific data. The newly discovered planet is about 2.5 million miles (4 million km) from Proxima Centauri, less than a tenth of Mercury’s distance from our sun.
The newly discovered planet, called “Proxima d”, orbits “Proxima Centauri” at a distance of about four million kilometers, less than a tenth of Mercury’s distance from the sun. It orbits the star and the habitable zone, the region around the star where liquid water can exist on a planet’s surface, and takes just five days to complete one orbit around Proxima Centauri.
It is already known that the star hosts two other planets: Proxima b, a planet with a mass similar to that of Earth and orbiting the star every 11 days and located within the habitable zone, and Proxima c, which completes its orbit around the star every five years.
Proxima b was discovered a few years ago using the HARPS instrument on the European Southern Observatory’s 3.6-meter telescope.
Confirmation of the discovery occurred in 2020 when scientists observed the “Proxima” system with a new instrument on the European Southern Observatory’s Very Large Telescope (ESO’s VLT), with greater accuracy, which it calls ESPRESSO.
During observations of the Very Large Telescope (VLT) and later, astronomers discovered the first hints of a signal corresponding to an object with a five-day orbit.
At only a quarter of the mass of Earth, Proxima d is the lightest exoplanet ever measured using the radial velocity technique, surpassing a recently discovered planet in the L 98-59 planetary system.
It is noteworthy that the gravitational effect of “Proxima D” is so small that it only causes “Proxima Centauri” to move back and forth at an estimated speed of about 40 centimeters per second (1.44 kilometers per hour).