COCONUTS-2b

COCONUTS-2 b is a gas giant exoplanet that orbits the M-type star L 34-26. With a mass of 7.3 Jupiters, it takes over one million years to complete one orbit around the star orbiting 7,500 AU away from it. The planet was discovered in 2011 and was initially identified as a T9 free-floating brown dwarf WISEPA J075108.79−763449.6. During the COol Companions ON Ultrawide orbiTS (COCONUTS) survey, its association with L 34-26 was announced in 2021. At a distance of 35.5 light-years (10.9 parsecs), COCONUTS-2b was the closest directly imaged exoplanet to Earth until Epsilon Indi Ab was imaged in 2024. The researchers found that it is unlikely that COCONUTS-2b was formed inside the protoplanetary disk of the host star and may instead have formed separately. The peculiar properties of COCONUTS-2b could be explained with different scenarios as proposed by Marocco et al. in 2024. The properties could be explained by a non-solar carbon-to-oxygen ratio, meaning that it formed inside a disk around L 34–26. In this scenario the most likely way COCONUTS-2b got in a higher orbit is by a stellar fly-by of two binaries or two planetary systems. In the second scenario L 34-26 is not actually young, but mimics youth due to tidal and/or magnetic interactions with an unseen companion.