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The new exoplanet was discovered with the help of the Very Large Telescope (VLT) of the European Southern Observatory (ESO) in Chile.
An international team of astronomers has discovered an exoplanet at least half the mass of Venus orbiting Barnard’s Star , the closest star to our Sun. Scientists do not rule out the possibility of three other exoplanets orbiting the star.
Located just six light-years away, Barnard is the nearest individual star to us, the fastest in the night sky, and the second closest star system in the neighborhood, after the three-star cluster Alpha Centauri .
Because of its proximity, this star is a prime target in the search for Earth-like exoplanets, but since 2018, when a team of astronomers discovered a super-Earth orbiting Barnard, no other planets had been discovered in its orbit.
That exoplanet, a super-Earth with three times the mass of Earth and an orbit of about 233 days, had characteristics that made life as we know it unviable.
The new exoplanet, which was discovered with the help of the Very Large Telescope (VLT) of the European Southern Observatory (ESO) in Chile, “is completely different” but equally inhospitable to hosting life, Alejandro Suárez Mascareño, a researcher at the Spanish Institute of Astrophysics of the Canary Islands (IAC) and co-author of the study, explained in statements to EFE.
Details of the new planet, named Barnard b, were published Tuesday in an article in the journal Astronomy & Astrophysics and are the result of observations made over the past five years.
Around Barnard
The team was looking for signs of possible exoplanets within Barnard’s star’s habitable or temperate zone, the range where liquid water can exist on the planet’s surface.
The astronomical community often focuses on the study of red dwarfs (such as Barnard) because low-mass rocky planets are easier to detect in their surroundings, something that is more complex to do if we are talking about larger stars, similar to the Sun.
The new exoplanet, Barnard b, is twenty times closer to Barnard’s star than Mercury is to the Sun, “has a surface temperature of about 125 ºC and an orbital period of 3.15 Earth days,” explained Suárez Mascareño.
“Barnard b is one of the lowest-mass exoplanets known and one of the few known with a mass less than that of Earth. But the planet is too close to the host star,” González Hernández added.
“Even if the star were about 2,500 degrees cooler than our Sun, it is still too hot to sustain liquid water on the planet’s surface,” the lead author concluded.
A super-Earth that doesn’t exist
To conduct this study, the team used ESPRESSO, a high-precision instrument that measures the wobble of a star caused by the gravitational pull of one or more orbiting planets.
Astronomers take advantage of this effect to measure with astonishing accuracy the changes in a star’s velocity due to an orbiting exoplanet.
The discovery of Barnard b was also confirmed by data from other instruments also specialized in the search for exoplanets: HARPS, at ESO’s La Silla Observatory , HARPS-N and CARMENES.
However, the new data has not confirmed the existence of the super-Earth reported in 2018. “We have not been able to confirm its existence and, in fact, at this time the general consensus is that this exoplanet might not exist,” Suárez Mascareño told EFE.
“But we believe that Barnard’s star could have up to three more exoplanets orbiting it, although for now we only have indications that we cannot confirm,” said the IAC researcher.
To do so, we will need to continue observing Barnard’s star, “but the discovery of this planet, along with other previous discoveries such as Proxima b and d, shows that our cosmic backyard is full of low-mass planets,” the researcher said.
ESO’s Extremely Large Telescope , currently under construction, will feature the ANDES instrument that will allow scientists to detect more of these small rocky planets in the temperate zone around nearby stars and study the composition of their atmospheres.
