VHS 1256–1257 Exoplanet System

Young triple brown dwarf system with roaring dust storms // VHS J125601. 92–125723. 9, or more simply VHS 1256–1257, is a real exoplanet system located 69. 0 light-years away in the constellation Corvus. It is a young system, 140 million years old, with an inner brown dwarf binary and an outer companion. The binary objects—named VHS 1256–1257 A and VHS 1256–1257 B—are thought to be near-identical, each weighing around 74 Jupiter masses and a little below the threshold to become a star. The pair are fairly hot with a modelled temperature of 2620 K (2347 °C) and an M7. 5 spectral type. They circle each other every 7. 3 years on highly eccentric orbits—among the highest ever seen in low-mass binaries. VHS 1256–1257 b is a third brown dwarf companion of spectral type L7 discovered around the twin hosts in 2015. A 2023 model constrained it to be ~16 Jupiter masses and ~1. 22 Jupiter radii in size, with a temperature near 1194 K (921 °C). However, these values do differ between analyses depending on initial assumptions. It follows an incredibly long ~16,000-year, highly eccentric orbit that is strongly misaligned—and possibly retrograde—relative to the inner binary. Strikingly, VHS 1256–1257 b also appears to be tilted ~90° on its side, similar to Uranus. An architecture of this kind is difficult to reconcile with standard theories of planet formation in a flat, rotating disk. Instead, recent work suggests the system likely formed through chaotic fragmentation of a collapsing gas cloud, in which the inner binary and the wide companion coalesced separately and inherited distinct spin and orbital orientations. There has even been speculation that a hidden fourth body in the system could have driven dynamical interactions that flipped the orbit into its current configuration. VHS 1256–1257 b is a prime candidate for atmospheric studies. It displays wild brightness fluctuations over a matter of hours and holds the record for the highest variability ever seen in a substellar object,