Barnard’s Star Hosts Newly Discovered Planets

Astronomers have uncovered strong evidence that Barnard’s Star, the second-closest star system to Earth, harbors not just one but four small planets.

Figure 1. Four Planets Confirmed Around Barnard’s Star After a Century of Searching.

Each of these planets has a mass ranging from 20% to 30% of Earth’s and orbits very close to its star, completing a full orbit within just a few days. Due to their proximity, they are likely too hot to sustain life. However, their discovery represents a major breakthrough in detecting smaller planets around nearby stars. Figure 1 shows Four Planets Confirmed Around Barnard’s Star After a Century of Searching.

The Century-Long Search for Planets

For over a hundred years, astronomers have studied Barnard’s Star in the hopes of discovering planets orbiting it. First identified by E. E. Barnard at Yerkes Observatory in 1916, this star is the closest single-star system to Earth. In contrast, our nearest stellar neighbor, Proxima Centauri, is part of a three-star system, which complicates planet formation and orbital dynamics.

Barnard’s Star belongs to a class of stars known as M dwarfs, which are now understood to be among the most abundant in the universe. Scientists are eager to learn more about the types of planets these stars host.

However, detecting planets around distant stars is a challenge. These planets are far too small to be directly observed against the overwhelming brightness of their stars, even with the most advanced telescopes. As a result, astronomers have had to develop innovative methods to find them.

This animation illustrates the orbital dynamics of the Barnard’s Star planetary system. For over a century, astronomers have studied Barnard’s Star in search of planetary companions. First identified by E. E. Barnard at Yerkes Observatory in 1916, it remains the closest known single-star system to Earth.

Now, with the help of the Gemini North telescope—part of the International Gemini Observatory, co-funded by the U.S. National Science Foundation and operated by NSF NOIRLab—astronomers have confirmed the existence of four sub-Earth exoplanets orbiting the star. Among them is the least massive exoplanet ever detected using the radial velocity technique, setting a new benchmark for discovering smaller planets around nearby stars.

Hunting Planets with Star Wobbles

One such search was led by UChicago professor Jacob Bean and his team, who developed and installed the MAROON-X instrument. Mounted on the Gemini Telescope atop a Hawaiian mountain, MAROON-X is specifically designed to detect distant planets.

Since stars vastly outshine their planets, astronomers focus on the effects planets have on their stars—similar to observing wind by watching a flag’s movement. MAROON-X detects one such effect: the gravitational tug of orbiting planets, which causes the star to wobble slightly. By measuring subtle color shifts in the star’s light with extreme precision, the instrument can determine the number and masses of planets responsible for these movements.

Basant, Bean, and their team carefully calibrated and analyzed data collected over 112 nights spanning three years. Their observations provided strong evidence for three planets orbiting Barnard’s Star. When they combined their findings with data from the ESPRESSO instrument—used in a separate study on the Very Large Telescope in Chile—they found compelling evidence for a fourth planet.

More Than Just Gas Giants

Scientists believe these newly discovered planets are likely rocky, rather than gas giants like Jupiter. Determining this with absolute certainty is challenging, however, because their orbits do not align in a way that allows astronomers to observe them passing in front of their star—a common method used to analyze a planet’s composition. Instead, researchers rely on data from similar planets around other stars to make informed estimates about their makeup.

Additionally, the team was able to rule out, with a high degree of confidence, the presence of other planets within Barnard’s Star’s habitable zone.

An Exciting Future for Discovery

These newly discovered planets are among the smallest ever detected using this technique, marking a significant step toward identifying more and more planets across the universe.

Most rocky exoplanets found so far are much larger than Earth and exhibit similar characteristics throughout the galaxy. However, scientists suspect that smaller planets could have a much wider range of compositions. As more of these planets are discovered, researchers can gain deeper insights into how they form—and what factors might make a planet capable of supporting life.

The Thrill of the Unknown

Beyond the scientific implications, the discovery itself was an exhilarating experience for the researchers.

“We worked on this data really intensely at the end of December, and I was thinking about it all the time,” said Jacob Bean. “It was like, suddenly we knew something that no one else did about the universe. We just couldn’t wait to share this secret.”

He reflected on the broader significance of the find: “A lot of what we do can feel incremental, making it hard to see the bigger picture. But this discovery is something humanity will hopefully know forever. That sense of uncovering something truly new is incredible.”

Source: SciTECHDaily

Cite this article:

Priyadharshini S (2025), "After A Century of Searching, Astronomers Confirm Four Planets Orbiting Barnard’s Star", AnaTechMaz, pp. 266