Physical Properties of Transneptunian Objects

摘要: In 1992, the first body beyond Neptune since discovery of Pluto in 1930 was found. Since then, nearly a thousand solid bodies, including some planetary size, have been discovered outer solar system, largely Neptune. Observational studies an expanding number these objects with spaceand groundbased telescopes are revealing unexpected diversity their physical characteristics. Their colors range from neutral to very red, intrinsic surface compositions and/or different degrees processing that they endured. While show no diagnostic spectral bands, others deposits ices H2O, CH4, and N2, sharing properties Triton. Thermal emission spectra suggest presence silicate minerals. Measurements thermal allow determinations dimensions albedos larger (diameter > ~75 km) members known population; geometric widely 2.5% >60%. Some 22 transneptunian (including Pluto) multiple systems. has three satellites, while 21 other representing about 11% sample investigated, binary one system where both mass radius reliably known, mean density primary is ~500 kg/m3, comparable comets [e.g., Comet 1P/Halley (Keller et al., 2004)].