Our "stellar neighbor", Proxima Centauri, continues to hold surprises: the latest comes in the form of a newly discovered planet. I study just released comes from Portugal and bears the signature of Joao Faria, researcher at the Instituto de Astrofísica e Ciências do Espaço. Proxima Centauri is the closest star to our sun, "just" 4,24 light years away.
The newly discovered planet is called Proxima d, and orbits Proxima Centauri at a distance of about four million kilometers. It is less than a tenth of Mercury's distance from the Sun. It completes an orbit around its star in just five days, and lies between it and the habitable zone (that area where water can also be found on the surface of a planet ).
Third "son" for Proxima Centauri
Our closest star Proxima Centauri is already known to host two other planets: Next b, with a mass comparable to that of the Earth (which orbits the star every 11 days and is always in the habitable zone), and Proxima v, which is located on a more distant star (it takes five years to orbit Proxima Centauri).
Proxima b was discovered in 2016 with the HARPS instrument on the ESO telescope. Four years later, in 2020, the discovery was confirmed by a much more precise instrument. It is about theEchelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO). It was during these more recent observations that astronomers spotted the first hints of a signal corresponding to another planet.
A new arrival
“After obtaining new data, we were able to confirm the signal,” says Faria. “I am excited by the prospect of discovering an exoplanet so close to Earth.”
At just a quarter of the mass of Earth, Proxima d is the lightest exoplanet ever discovered by the radial velocity method. The technique works by detecting small fluctuations in a star's motion caused by the gravitational pull of an orbiting planet.
“It's an extremely important discovery,” he says Pedro Figueira, ESPRESSO instrument scientist at ESO in Chile. “It shows that the technique of radial speed it has the potential to reveal an entire population of planets like ours, which are expected to be the most abundant in our galaxy and which can potentially host life as we know it.”
Espresso and his brothers
This result clearly shows what ESPRESSO is capable of: I wonder what it will be able to find in the future, and when it will be completed by its “companion” ELT, Extremely Large Telescope, currently under construction in the Atacama Desert. It will be crucial to discover and study many other planets around nearby stars.
The search continues!
