New planetary mass object discovered in quadrupole system

This week’s photo shows the unique star system HIP 81208, taken by ESO’s Very Large Telescope (VLT) in Chile. Astronomers believe that HIP 81208 is a system consisting of a giant central star (A, the central bright spot), a brown dwarf (B) orbiting it, and a low-mass star (C) in a more distant orbit. However, a new study has revealed a never-before-seen hidden gem: an object (Cb), about 15 times more massive than Jupiter, orbiting the smaller of the two stars (C). The discovery of Cb means that HIP 81208 is a particularly intriguing system with two stars and two smaller objects orbiting each star –– in other words, a quaternary system. The mass of newly discovered object Cb puts it right on the boundary between planets and brown dwarfs – failed stars that are not massive and hot enough to fuse hydrogen into helium. The hidden giant Cb was discovered when a team of astronomers, led by A. Chomez of the Paris Observatory, reanalyzed archival data from the high-contrast Exoplanet Research instrument Spectro -Polarimetric (SPHERE) installed on VLT.

While many other tools use indirect methods to search for distant worlds, SPHERE uses a technique called direct imaging: what we see here is an actual image of the system. Indeed, this is the first hierarchical four-level system discovered through direct imaging, which will prove invaluable in understanding how complex systems like this form and evolve.

Source: ESO/A. Chomez et al.