We may have a new planetary neighbor orbiting just four light-years away.
Astronomers have detected evidence of a third planet orbiting Proxima Centauri, our Sun’s closest stellar neighbor, 40.2 trillion kilometers away.
A light year, the distance light travels in one year in a vacuum, is equivalent to about 9.46 trillion kilometers. With a mass of about a quarter of Earth’s mass, the rocky object is one of the lightest exoplanets ever found.
A study detailing the discovery was published Thursday in the journal Astronomy & Astrophysics.
The small, faint red dwarf star is just one-eighth the mass of the Sun and already harbors a confirmed Earth-sized planet and possibly a second most distant planet candidate.
Possible conditions for life
This last planet detected, called Proxima d, completes an orbit around the star every five Earth days. It is only about 4 million kilometers from the star, which is less than a tenth of the distance between Mercury and the Sun in our Solar System.
As the closest planet to the Sun, Mercury completes an orbit around it every 88 days.
The first planet found in the system, Proxima b, was confirmed in 2020. It is the size of Earth and orbits the star every 11 days.
It exists within the habitable zone, that is, the distance from a star where conditions are right for liquid water, one of the main ingredients for life as we know it, to exist on the surface of the planet.
As far as its neighbors are concerned, Proxima d is too close to the star to be in the habitable zone, and Proxima c, which takes about five years to orbit the star, is too far away.
“The discovery shows that our closest stellar neighbor seems to be full of interesting new worlds, within the reach of further studies and future explorations,” said lead author João Faria, a researcher at the Instituto de Astrofísica e Ciências Espacials in São Paulo, in a note. Portugal, in a statement.
Astronomers found Proxima d using the European Southern Observatory’s Very Large Telescope in Chile. The observatory’s telescopes and instruments were used to find and confirm previous discoveries of planets in the Proxima Centauri system.
During recent follow-up observations of the system, astronomers detected a faint signal from an object in a fast orbit around the star.
More observations were carried out using the highly sensitive Echelle Spectrograph for Rocky Exoplanets and Stable Spectroscopic Observations instrument, known by the acronym ESPRESSO, on the Very Large Telescope.
The data suggested that there was a possible planet present and that its gravitational pull was pulling on the star rather than changes in the star.
“After obtaining new observations, we were able to confirm this signal as a new planet candidate,” Faria said.
“I was excited about the challenge of detecting such a small signal and, in doing so, discovering an exoplanet so close to Earth.”
Future observations of the planet candidate may confirm that Proxima d is indeed the third known world to orbit this star.
A method for identifying Earth-like planets
The exoplanets around Proxima Centauri were found using the indirect radial velocity method, when the gravity of an orbiting object pulls on a star and causes it to wobble slightly, rather than observing dips in starlight as planets pass in the orbit. in front of them, called the transit method.
But this is the first time the radial velocity method has been used to find such a light planet.
“This achievement is extremely important,” said Pedro Figueira, scientist of the ESPRESSO instrument, in a statement.
“This shows that the radial velocity technique has the potential to reveal a population of light planets, like our own, that are expected to be the most abundant in our galaxy and that could potentially host life as we know it.”
The researchers believe that future observations could still reveal more details and even additional planets within the system.
“This result clearly shows what ESPRESSO is capable of and makes me wonder what it might find in the future,” said Faria.
Source: CNN Brasil
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