Four small planets discovered orbiting the nearest single star to Earth

Barnard’s Star has long been a focus of interest for people who study worlds beyond our solar system. It sits about six light-years from Earth and is known for its quick motion across our sky.

For years, astronomers have wondered whether it might harbor planets that could help us understand how planetary systems form.

Now, they seem to have gotten their wish. Recent observations suggest there may be four miniature planets orbiting Barnard’s Star.

Each is calculated to be just 20 to 30% the mass of Earth and completes one full trip around the star in only a few days.

These findings have caught many people’s attention because they point to greater precision in detecting smaller, more elusive planets.

“It’s a really exciting find – Barnard’s Star is our cosmic neighbor, and yet we know so little about it,” said Ritvik Basant, Ph.D. student at the University of Chicago and first author on the study. “It’s signaling a breakthrough with the precision of these new instruments from previous generations.”

Understanding Barnard’s Star – the basics

Barnard’s Star first came to light in 1916, thanks to astronomer E. E. Barnard at Yerkes Observatory. Ever since, scientists have been keeping an eye on it.

They nicknamed it a “great white whale” because people have often claimed to see planets there, only to be disappointed later. This time, the work is featured in The Astrophysical Journal Letters, dated March 11.

Observers used to rely on less sensitive equipment, which sometimes produced conflicting signals. That is one reason the star became such a legend among planet hunters, who occasionally thought they had proof but eventually realized their results were inconclusive.

Experts point out that Barnard’s Star is the closest single-star system after the Sun. In contrast, the nearest star system overall, Proxima Centauri, has three stars in a gravitational dance.

The difference matters because multiple stars complicate how planets might form, so an M dwarf star with just one companion star suggests a different environment for potential worlds.

Hunting planets with MAROON-X

Astronomers cannot directly see tiny planets close to bright stars. Instead, they track the gentle pull each planet exerts on its star.

A specialized instrument called MAROON-X, installed on the Gemini Telescope in Hawaii, can detect faint wobbles in a star’s light signal. With this approach, the group detected three planets around Barnard’s Star.

The fourth emerged when they combined their work with data from an earlier observation, taken by an instrument called ESPRESSO in Chile.

“We observed at different times of night on different days. They’re in Chile; we’re in Hawaii. Our teams didn’t coordinate with each other at all,” said Basant. “That gives us a lot of assurance that these aren’t phantoms in the data.”

Barnard’s Star’s planets

Scientists suspect the new finds are small, rocky worlds, though exact compositions are hard to confirm.

The angle from Earth means these planets do not appear to pass in front of their star, so the usual tests to identify rock or gas are out of reach.

However, these orbits are probably far too close to the star for comfortable conditions.

“We worked on this data really intensely at the end of December, and I was thinking about it all the time,” reflected Jacob Bean, a professor at the University of Chicago.

“It was like, suddenly we know something that no one else does about the universe. We just couldn’t wait to get this secret out,” Bean added.

A sense of excitement fueled the entire project.

“A lot of what we do can be incremental, and it’s sometimes hard to see the bigger picture,” Bean enthused. “But we found something that humanity will hopefully know forever. That sense of discovery is incredible.”

What happens next?

Barnard’s Star’s four worlds rank among the tiniest bodies confirmed with such radial velocity tools.

Many rocky exoplanets discovered so far tend to be larger than Earth, and patterns among them appear consistent across the galaxy.

Astronomers want to see if smaller ones show diverse compositions that might hint at how they form.

M dwarfs, which are abundant in the universe, are known to have intense magnetic activity, and that may affect how planets develop.

Why Barnard’s Star’s planets are important

Understanding these processes could unlock clues about which stars are most likely to host stable surfaces.

Some hope these insights will guide future searches for life, even though these particular worlds lie in scorching territory.

Researchers will keep refining their techniques to look for planets in more temperate zones. Each fresh advance in instrumentation increases the odds of uncovering new surprises.

Additional surveys may also shed light on whether tiny planets form more often around cooler stars, or if conditions for habitability vary in unexpected ways.

With every improved telescope, the possibility of spotting something remarkable grows.

The full study was published in The Astrophysical Journal Letters.

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