Exoplanet found around our closest lone star
An exoplanet has been discovered orbiting the nearest single star to Earth (apart from the Sun), only 6 light-years away.
The nearest stars to our solar system are in the Alpha Centauri system at just 4.2 light-years away. This triple star system is in the Centaurus constellation. The closest exoplanets to Earth were discovered orbiting one of the Alpha Centauri stars, Proxima Centauri, in 2016.
But the new exoplanet has been found orbiting Barnard’s star – the nearest lone star to our solar system.
Barnard’s star has long been thought to be a prime candidate for the detection of Earth-like exoplanets. A false alarm in 2018 might have dashed hopes. But astronomers are a patient bunch.
“Even if it took a long time, we were always confident that we could find something,” says Jonay González Hernández, a researcher at the Instituto de Astrofísica de Canarias in Spain, lead author of the Astronomy & Astrophysics paper announcing the planet’s discovery.
The planet, Barnard b, is about half the mass of Venus and orbits Barnard’s star once every 3.15 Earth days. Its orbit is 20 times less than the distance between Mercury and the Sun, but since Barnard’s star is much cooler than our Sun, the planet’s surface temperature is “only” about 125°C.
“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, closer than the habitable zone,” explains González Hernández. “Even if the star is about 2,500 degrees cooler than our Sun, it is too hot there to maintain liquid water on the surface.”
Small, rocky planets are easier to spot around low-mass red dwarf stars like Barnard’s star than around brighter stars like our Sun.
Barnard b was spotted using data from the European Southern Observatory’s Very Large Telescope in Chile.The team says the data also includes hints of 3 more exoplanets around Barnard’s star. But further observation is needed to confirm these signals.
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