Tiny Earth-Like World Discovered Orbiting Nearest Single Star to Earth

An infographic showing the nearest stars to the Sun. (IEEC / Scince-Wave - Guillem Ramisa)

By Michelle Starr

The nearest single star to the Solar System has just yielded up a rare and wonderful treasure.

Around a red dwarf known as Barnard's star, which lies just 5.96 light-years away, astronomers have found evidence of an exoplanet.

And not just any exoplanet. This fascinating world, known as Barnard b, is tiny, clocking in with a minimum mass of 37 percent of the mass of Earth. That's a little shy of half a Venus, and about 3.5 Marses.

The reason it's so marvellous is that tiny exoplanets are really, really hard to find. Although Barnard b is not habitable to life as we know it, its discovery is leading us closer to the identification of Earth-sized worlds that may be scattered elsewhere throughout the galaxy.

The discovery follows hints of a possible planetary signal orbiting the star in 2018. That hypothesised exoplanet was thought to be around three times the mass of Earth, orbiting at a distance of about 0.4 astronomical units.

Animation showing how radial velocity is measured. (Alysa Obertas/Wikimedia Commons, CC BY-SA 4.0)

Though any planet matching that mass or distance is yet to be confirmed, the more teensy Barnard b emerged after researchers conducted a careful campaign to observe the star. What's more, there might be three more exoplanets lurking even further from the star, out where they're harder to spot.

"Even if it took a long time," says astronomer Jonay Isai González Hernández of the Institute of Astrophysics of the Canary Islands in Spain, "we were always confident that we could find something."

First published at Science Alert, October 2, 2024

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