An international team of astronomers, with significant contributions from UK researchers, has announced the discovery of Beta Pictoris d, a new exoplanet orbiting the nearby star Beta Pictoris. This gas giant is notable for being the faintest exoplanet ever directly imaged from Earth, a significant achievement in the field of exoplanetary science.
The discovery, published in ‘The Astrophysical Journal Letters’, was made using the Enhanced Resolution Imager and Spectrograph (ERIS) instrument on the European Southern Observatory’s (ESO) Very Large Telescope in Chile. A crucial component of ERIS is the NIX infrared camera, which was developed and built by the Science and Technology Facilities Council’s (STFC) UK Astronomy Technology Centre (UK ATC) in Edinburgh, in collaboration with ETH-Zurich and Leiden University. Much of the UK research effort was also supported by the STFC.
Dr Ben Sutlieff, an astronomer at the University of Edinburgh and co-lead of the study, described the find as a “serendipitous discovery.” Initially, the team intended to observe Beta Pictoris b, a previously known planet in the system, to study its changes over time. However, during the analysis of their images, they detected an unexpected object, leading to the identification of Beta Pictoris d.
Beta Pictoris d is a gas giant, similar to Jupiter and Saturn, but at approximately 2.4 times the mass of Jupiter, it is considerably lighter than the other two known planets in its system. Its extreme faintness, being 100 times dimmer than Beta Pictoris b, posed a substantial technical challenge for direct imaging, which involves capturing light directly from the planet rather than inferring its presence from its host star.
The Beta Pictoris system, located 63 light-years from Earth, now boasts at least three directly imaged planets, making it only the second such system known, after HR 8799. This multi-planet system offers a unique opportunity for astronomers to study different exoplanets that formed within the same stellar environment, providing valuable insights into planetary formation and evolution.