Astronomers discover 4 rocky planets orbiting Barnard’s Star

Keele (UK): Barnard's Star, a small and dim red dwarf, is one of the closest stars to Earth, with its light taking only six years to reach us. Despite its proximity, it remains too faint to be seen with the naked eye. Now, astronomers have discovered four small planets orbiting this star, marking a significant breakthrough in planetary detection. Teams from America and Europe utilized precision instruments on the world's largest telescopes to achieve this discovery.

Barnard's Star, closer in size to Jupiter than to the Sun, is the fourth closest stellar system to Earth, following the three-star Alpha Centauri system. The newly detected planets are too faint to be seen directly, but their presence was confirmed through their gravitational influence on the star. This effect creates a rhythmic motion, which is detected using highly sensitive spectrograph instruments that analyze the star’s light by splitting it into its component wavelengths.

Detecting these planets posed a significant challenge due to the star’s own behavior. Red dwarf stars, like Barnard's Star, exhibit intense magnetic activity, including storms on their surfaces that can mimic planetary signatures. To overcome this, astronomers deployed advanced spectrographs on powerful telescopes, observing the star over extended periods and meticulously calibrating data to filter out stellar magnetic noise.

In 2024, a research team led by Jonay Gonzalez Hernandez from the Canary Islands Astrophysics Institute reported four years of observations using the Espresso spectrograph on the European Southern Observatory’s Very Large Telescope in Chile. Their findings indicated the presence of one definite planet and tentative signals of three more. Later, a team led by Ritvik Basant from the University of Chicago incorporated three additional years of data from the Maroon-X instrument on the Gemini North telescope. Their analysis confirmed the existence of three planets, and when combined with the previous dataset, it verified all four.

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Scientific discoveries that push technological boundaries often require careful scrutiny to rule out instrumental or computational errors. The independent confirmation of these planets using different telescopes and instruments strengthens confidence in their existence. The newly discovered planets form a compact system with short orbital periods ranging from two to seven Earth days, in stark contrast to Mercury’s 88-day orbit around the Sun. These planets are likely smaller than Earth, composed of rocky material, and exposed to intense radiation from Barnard’s Star, making them inhospitable for liquid water or atmospheres.

Efforts to detect additional planets in the star’s habitable zone have so far been unsuccessful. Details about the planets’ exact sizes remain unknown, as their orientation does not allow for transit observations, which would measure how much starlight they block while passing in front of the star. However, these findings provide valuable insights into planetary formation. The planets likely originated in a protoplanetary disk around Barnard’s Star, where dust particles gradually coalesced into larger bodies over time.

Red dwarfs are the most common type of star in the galaxy, and the frequent discovery of planets around them suggests that planetary systems may be more prevalent than stars themselves. Most known exoplanets are located close to their stars, primarily because their gravitational influence makes detection easier, and their shorter orbits allow astronomers to collect sufficient data in less time. The upcoming European Space Agency’s Plato mission, scheduled for launch in 2026, aims to uncover more planets further from their stars, particularly those in habitable zones. This could offer deeper insights into planetary distributions and determine whether our Solar System, which lacks close-in planets, is an anomaly in the galaxy.

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With PTI inputs