Sednoid

A sednoid is a trans-Neptunian object with a large semi-major axis, a distant perihelion and a highly eccentric orbit, similar to that of the dwarf planet Sedna. The consensus among astronomers is that there are only four objects that are generally agreed to belong to this population: Sedna, 2012 VP113 ("Biden"), 541132 Leleākūhonua, and 2023 KQ14 ("Ammonite"). All four have perihelia greater than 60 AU. The sednoids are also classified as detached objects, since their perihelion distances are large enough that Neptune's gravity does not strongly influence their orbits. Some astronomers consider the sednoids to be Inner Oort Cloud (IOC) objects. The inner Oort cloud, or Hills cloud, lies at 1,000–10,000 AU from the Sun. One attempt at a precise definition of sednoids is any body with a perihelion greater than 50 AU and a semi-major axis greater than 150 AU. However, this definition applies to the objects 2013 SY99, 2020 MQ53, and 2021 RR205 which have perihelia beyond 50 AU and semi-major axes over 700 AU. Despite this, most astronomers do not classify these objects as sednoids because their orbits still experience gradual orbital migration as a result of perturbations by galactic tides and Neptune's weak gravitational influence. With their high eccentricities (greater than ~0.7), sednoids are distinguished from the high-perihelion objects with moderate eccentricities that are not affected by perturbations from Neptune, namely 2015 KQ174, 2015 FJ345, (612911) 2004 XR190 ("Buffy"), (690420) 2014 FC72 and 2014 FZ71.