ASTRONOMERS DISCOVER FAINTEST PLANET IMAGED FROM EARTH

Astronomers have discovered a third planet orbiting the star Beta Pictoris, designated Beta Pictoris d. The discovery was made using the European Southern Observatory's Very Large Telescope and published in The Astrophysical Journal Letters. The planet is 100 times fainter than Beta Pictoris b, the first planet identified in the system, and ranks among the lightest exoplanets ever imaged from Earth's surface. The detection was initially serendipitous; researchers noticed the additional object whilst analysing images of Beta Pictoris b.

Upon closer examination of archival observations held by the European Southern Observatory, the team identified Beta Pictoris d in multiple images spanning more than 11 years. The planet had been present in the data since observations made over a decade ago, including in photographs where it was barely visible against the brightness of its larger neighbour. Like the two other planets in the system, Beta Pictoris d is a gas giant comparable to Jupiter or Saturn. However, it orbits at a considerably greater distance than Beta Pictoris b and Beta Pictoris c, and its mass is approximately 2.4 times that of Jupiter—substantially lighter than the other two planets, which each measure around 10 times Jupiter's mass.

The newly discovered planet is relatively cold compared to its host star, which accounts for its extreme faintness and made detection from Earth particularly challenging. Ben Sutlieff of the University of Edinburgh, co-lead of the study, noted that the team had originally sought to monitor changes in Beta Pictoris b over time before identifying the additional object. Markus Bonse of the European Southern Observatory and Jayne Birkby of the University of Oxford also contributed to the research. The discovery demonstrates that substantial celestial bodies can remain undetected in archival observations for extended periods.