SANTA CRUZ DE TENERIFE, 1st October (EUROPA PRESS) –
The nearest isolated star to our Sun is known as Barnard, and a research team led by the Institute of Astrophysics of the Canary Islands (IAC) has recently discovered that it possesses a ‘sub-Earth’ orbiting it. The exoplanet identified, termed Barnard b, has at least half the mass of Venus and orbits its star at a rapid pace, resulting in a year lasting slightly more than three Earth days.
This newly detected exoplanet is seventeen times closer to Barnard’s star than Mercury is to the Sun and boasts a surface temperature of roughly 125°C, rendering the presence of liquid water on its surface impossible.
This significant discovery, spearheaded by the IAC in collaboration with various international centres, was made possible through images captured by the ESPRESSO spectrograph mounted on the Very Large Telescope (VLT) of the European Southern Observatory (ESO), situated at the Paranal Observatory in Chile. Findings have been published in the journal Astronomy & Astrophysics.
The same research also indicates the presence of three additional candidate objects that may be exoplanets orbiting the same star, reaffirming the notion that our solar neighbourhood is an increasingly promising area to find Earth-like planets that could support life in solar systems akin to our own.
Following Alpha Centauri, Barnard represents the nearest stellar system to the Solar System, located just 6 light years away from Earth. This proximity, coupled with its classification as a red dwarf type star, has led scientists to observe it since 2018.
Jonay González Hernández, the lead author of the study and an IAC researcher, states, “Although it has taken several years, we were convinced that in this system, due to its closeness to the Sun, the conditions were favourable for discovering a planet analogous to Earth.”
The research team has dedicated recent years to identifying signs of potential exoplanets situated within the habitable or temperate zone of Barnard’s star—an area where liquid water could potentially exist on the planet’s surface.
In this regard, González Hernández elaborates, “Barnard b is one of the least massive exoplanets known and among the few with a mass lower than that of Earth. However, the planet is situated too close to its host star, falling outside the habitable zone,” and adds, “while the star is approximately 2,500 degrees cooler than our Sun, the surface of the planet is excessively hot to sustain liquid water.”
A DISCOVERY WITH THE ASSISTANCE OF ESPRESSO
To achieve this discovery with the VLT, the team utilized the ESPRESSO (Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations) instrument—an ultra-stable, high-resolution spectrograph designed to seek and characterise Earth-like planets along with studying variations in fundamental astrophysical constants, co-led by the IAC, which contributed to its design and construction.
The ESPRESSO instrument enabled the study of stellar variations induced by the gravitational pull of one or several orbiting planets. These results were later corroborated with data from other instruments also dedicated to exoplanet detection, such as HARPS at ESO’s La Silla Observatory and CARMENES at the Calar Alto Observatory (Almería).
The research team is continuing to investigate the three candidate exoplanet objects around this star to verify whether they will indeed be confirmed as exoplanets. “We now need to persist in observing this star to validate the signals of the remaining candidates,” remarks Alejandro Suárez Mascareño, another researcher at the Institute of Astrophysics of the Canary Islands and co-author of the study. “The detection of this planet, complemented by earlier finds such as Proxima b and d, illustrates that our ‘cosmic backyard’ is abundant in low-mass planets.”
This research has also seen the involvement of other IAC scientists, including Rafael Rebolo, Atanas Stefanov, Nicola Nari, Vera Passegger, Carlos Allende Prieto, Ricardo Génova, and Enric Pallé.
