They discovered an exoplanet orbiting Barnard’s star – DW – 01/10/2024
An international team of astronomers has discovered an exoplanet at least half the mass of Venus orbiting Barnard’s Star, the star closest to our Sun. Scientists do not rule out that there are three more exoplanets in other orbits of the star.
Located just six light-years away, Barnard is our closest single star, the fastest in the night sky, and the second closest star system in the area behind the three-star group Alpha Centauri.
Because of its proximity, the 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 have been discovered in its orbit.
This exoplanet, a super-Earth, three times the mass of Earth and orbiting for about 233 days, had characteristics that made life as we know it unviable.
The new exoplanet, discovered by the European Southern Observatory’s (ESO) Very Large Telescope (VLT) in Chile, is “completely different” but equally inhospitable to life, Alejandro Suarez Mascareno explained in statements. EFE, researcher at the Spanish Institute of Astrophysics of the Canary Islands (IAC) and co-author of the study.
Details of the new planet, named Barnard b, were published Tuesday in a paper in the journal Astronomy & Astrophysics and are the result of observations made over the past five years.
“Even though it took us a long time, we were always confident that we could find something,” said Jonay Gonzalez Hernandez, an IAC researcher and lead author of the paper.
Around Barnard
The team looked for signs of possible exoplanets in the habitable or temperate zone of Barnard’s Star – the range where liquid water could exist on the planet’s surface.
Often the astronomy community focuses on studying red dwarfs (like Barnard) because low-mass rocky planets are easier to detect in their environment, which is more difficult to do with larger stars like the Sun.
The new exoplanet, Barnard b, is twenty times closer to Barnard’s star than Mercury is to the Sun. “It has a surface temperature of about 125 ºC and an orbital period of 3.15 Earth days,” explained Suarez Mascareno.
“Barnard b is one of the lowest mass exoplanets known and one of the few known with a mass less than Earth. But the planet is too close to its parent star,” added Gonzalez Hernandez.
“Even if the star were about 2,500 degrees cooler than our Sun, it is too hot to support liquid water on the planet’s surface,” the lead author concluded.
Super-Earth that doesn’t exist
For 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 are using this effect to measure with amazing precision how a star’s speed changes due to an exoplanet orbiting it.
Barnard b’s discovery was also confirmed by data from other instruments also specialized in searching for exoplanets: HARPS at ESO’s La Silla Observatory, HARPS-N and CARMENES.
However, the new data did not confirm the existence of the super-Earth that was reported in 2018. “We have not been able to confirm its existence, and in fact the general consensus at present is that this exoplanet could not exist,” Suárez Mascareño moved to EFE.
“But we believe that there may be up to three more exoplanets around Barnard’s star, although at the moment we only have signs that we cannot confirm,” the IAC researcher emphasized.
To do this, we will have 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 yard is full of low-mass planets,” the researcher emphasized.
ESO’s Extremely Large Telescope, currently under construction, will be equipped with the ANDES instrument, which will allow the scientific community to discover more of these small rocky planets in the temperate zone around nearby stars and study the composition of their atmospheres.
el(EFE, astronomy and astrophysics)