New Neighbors

For more than 50 years, astronomers have hunted unsuccessfully for planets that orbit Barnard’s star, the star closest to our solar system. They knew some were there but couldn’t find them – with each claim eventually being refuted – until now. 

“Finding exoplanets around Barnard’s star has been something of a white whale for astronomers,” wrote the American Astronomical Society. “Now the white whale appears to have been caught – at last.” 

Researchers found four planets orbiting the star, which is six light years away, they said in a new study.  

They did this by using data collected by the Hawaii-based Gemini Telescope and the Chile-based Very Large Telescope: In November, astronomers found one planet last year via a study based on data gathered through the Very Large Telescope, which hinted that there were more.  

Those hints come from the “wobble” method, also known as “radial velocity.” When a planet orbits its star, the planet’s gravity tugs on the star, causing a slight wobble that is visible to modern telescopes. 

The newly discovered planets fall into the category of exoplanets, meaning they orbit stars outside of Earth’s solar system. These four are among the smallest of more than 5,800 exoplanets discovered since the 1990s, and scientists say they are too hot to sustain life. 

“A key requirement for habitability is the presence of liquid surface water,” the lead author of the study, Ritvik Basant, told Reuters. “If a planet orbits too close to its star, any water would evaporate. If it’s too far, it would freeze. It turns out, all four planets orbiting Barnard’s star are too close to their host, making them too hot to sustain liquid water.” 

Barnard’s star is a red dwarf, the smallest type of regular star. And while it is much cooler than Earth’s Sun, its four neighboring planets are very close and cause intense heat. 

When looking for extraterrestrial life, researchers look for rocky and warm planets like Earth. While the newly found planets are not in the habitable zone – where surface temperatures allow for liquid water – scientists have not ruled out the existence of other small planets in Barnard’s star system and say the technology is helping to find new planets. 

“This study showcases the growing capabilities of next-generation instruments in detecting low-mass planets,” said Basant. “This marks a significant step forward in the search for Earth-mass planets within the habitable zones of sun-like stars.”