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07/15/2026 14:00
A New Planet in the Beta Pictoris System
Astronomers have discovered the gas giant Beta Pictoris d, orbiting the star Beta Pictoris. Weighing approximately 2.4 times the mass of Jupiter, it ranks as one of the lightest exoplanets ever captured directly in images. Its orbit lasts 91 years at a distance of 26 astronomical units. This discovery was made possible through data from the Very Large Telescope (VLT) and the James Webb Space Telescope (JWST), supplemented by archival images spanning over a decade. Beta Pictoris is the second system known to host more than two directly imaged planets, providing new insights into planetary formation and atmospheres.
The Discovery of Beta Pictoris d
An international research team, including MPIA researchers Elisabeth Matthews and Iain Hammond, has identified a third planet orbiting the star Beta Pictoris. This new planet, designated Beta Pictoris d, is a hundred times fainter than Beta Pictoris b, the first known planet in this system, and qualifies as one of the lightest exoplanets that can be directly observed from Earth.
After spotting the planet with the European Southern Observatory’s Very Large Telescope (VLT) and its new instrument ERIS, the researchers led by Ben Sutlieff (University of Edinburgh) and Markus Bonse (European Southern Observatory, Max Planck Institute for Intelligent Systems) made another key discovery. The planet had been hiding in previous observational data collected over more than a decade.
A Collaborative Success with JWST
Separately, another team led by Aidan Gibbs (University of California, San Diego) confirmed the existence of this planet using the JWST. Their results complement each other effectively. “While we can determine fundamental properties like temperature and mass from the direct light of Beta Pictoris d, Webb’s spectra reveal the planet’s atmosphere, showcasing signatures of methane (CH4), carbon monoxide (CO), and water vapor (H2O),” explains Matthews, who significantly contributed to the atmospheric analysis of the VLT observations.
Serendipitous Discovery
This finding was unexpected; the team was actually investigating brightness variations of planet Beta Pictoris b. However, during their analysis of the recordings, they stumbled upon another signal distinct from Beta Pictoris b, steering the research into a new direction.
To validate their discovery, the team scoured the ESO’s scientific data archive. Among these historical images dating back up to eleven years, they found the newly discovered planet visible in several frames, one of which showed it barely distinguishable from the dazzling light of its larger neighbor, Beta Pictoris b. This suggests that the new planet had played a game of hide-and-seek with astronomers for over a decade.
Planet Characteristics
Beta Pictoris d, like the other two planets in the system, is a gas giant similar to Jupiter or Saturn. While the two other bodies boast approximately ten times Jupiter’s mass, Beta Pictoris d has only 2.4 times Jupiter’s mass. Consequently, it stands out as one of the lightest planets directly photographed from Earth. Its size exceeds Jupiter’s by only about 30%, likely making Beta Pictoris d considerably more similar to the gas giants in our solar system than many other known exoplanets.
However, the new planet orbits at a far greater distance than any known gas giant in our solar system or even within the Beta Pictoris system itself. With an orbital radius of 26 astronomical units (AU), Beta Pictoris d resides between Uranus and Neptune in our solar system. It takes 91 years to complete one orbit.
Understanding the Environmental Impact
With an estimated surface temperature of around 600 Kelvin (about 325 degrees Celsius), Beta Pictoris d emerges significantly hotter than the gas planets in our solar system. This heat is attributed to the young age of the Beta Pictoris system, estimated at around 23 million years. These planets remain heated from their formation and continue to radiate warmth while collapsing under their gravity. Over time, Beta Pictoris d will cool, similar to Jupiter and Saturn in their developmental phases. Nevertheless, compared to many other directly imaged gas giants, this planet is relatively cool and emits extremely weak radiation compared to its parent star.
Archive Data: A Key to Confirmation
Typically, confirming a planet discovery requires new, time-consuming follow-up observations. However, “this system has already been intensely studied, resulting in a wealth of observations in the archives of ESO and JWST,” states Iain Hammond, who analyzed observational data spanning a decade. “Once we knew where to search for the potential new planet, it became clear it had been hidden in the data all along.” This discovery exemplifies how an open data policy enhances and promotes scientific advancement.
Future Prospects in Exoplanet Research
Beta Pictoris is now only the second system, after HR 8799, known to contain more than two directly imaged planets. “Systems with multiple directly imaged exoplanets represent the ‘holy grail’ of observational astronomy,” asserts Ben Sutlieff. They provide crucial insights into how different planets develop under identical formation circumstances.
This new find is particularly valuable as it is part of a three-planet system belonging to a very precisely defined stellar group. “This gives us a rare opportunity to directly compare the atmospheres of planets in a controlled environment and understand how their parent star influences their formation and development,” notes Matthews. They found that the atmosphere of Beta Pictoris d bears striking similarities to that of 51 Eri b, a planet belonging to the same star group.
In conclusion, Beta Pictoris d not only answers longstanding mysteries within its home system but also inspires future campaigns aimed at hunting for faint planets hidden within existing images. The scientific community is optimistic about new advances from the Extremely Large Telescope (ELT) and other upcoming instruments. The MPIA is actively involved in these instruments to enhance the discovery of numerous other worlds through direct imaging.
