Since the turn of the century, astronomers studied Barnard’s star with hopes to discover planets. E.E. Barnard discovered it at Yerkes Observatory, in 1916. It is Earth’s nearest star system. Using the MAROON X instrument, which is part of the International Gemini Observatory of NSF, astronomers have confirmed the existence of three exoplanets orbiting Barnard’s Star. Two of these were classified previously as candidates. The astronomers combined the data collected by MAROON-X and the ESPRESSO on ESO’s Very Large telescope to confirm the existence a fourth exoplanet, converting it from a candidate into a real one.
Artist’s rendition of Barnard’s Star’s exoplanets. Credit: International Gemini Observatory/NOIRLab/NSF/AURA/P. Marenfeld. Barnard’s Star is an M3.5 type star in Ophiuchus constellation. It is located at a distance of nearly six light years from the Sun, making it the second closest star after Alpha Centauri’s triple stellar system. Barnard’s Star, also known as Gliese699 or GJ699 due to its low level of activity and slow rotation is believed to be over 10 billion years. The new study claims that the star is home to at least four small planets. Each one has a mass between 20 and 30% of Earth. The planets are so near their star, they can zip around it in just a few days. This means that they’re too hot for them to be habitable. However, the discovery is an important benchmark in discovering planets near nearby stars. It’s an exciting discovery — Barnard’s star is our nearest neighbor and we still know very little about it,” Ritvik Basant said, a Ph.D. candidate at the University of Chicago. It’s a sign of a new era in precision for these instruments.
Stars are brighter and more visible than planets.
By observing the movement of a flag, we can see the effects planets may have on stars.
MAROON’s instrument searches for this effect. The gravity of the planets tugs on the position of the stars, causing the star to appear to move back and forth. The MAROON-X instrument measures the color so accurately that it is able to detect these small shifts. It can even determine the mass and number of planets which must be orbiting the star in order for this effect. Basant and his colleagues thoroughly calibrated and analysed data collected over 112 nights in a three-year period. The team found strong evidence that three planets orbit Barnard’s Star. The team found good evidence of a fourth world when they combined the data collected by the ESPRESSO with their own findings. The astronomers stated that these planets were likely to be rocky, and not gaseous like Jupiter. It will be hard to determine with certainty if they are rocky or not, because we cannot see their stars from Earth.
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Ritvik Basant et al. 2025. Four sub-Earth planets orbiting Barnard’s Star as seen from MAROON X and ESPRESSO. ApJL982, L1; doi: 10.3847/2041-8213/adb8d5
