DWARF PLANET 136199 ERIS AND ITS SATELLITE

According to the Minor Planet Center catalog, the dwarf planet Eris is the second largest after Pluto and the most massive and farthest dwarf planet from the Sun in the Solar System. After 24.08.2006, Eris and Pluto updated their status and became dwarf planets. In July 2015, after the data obtained by the New Horizons spacecraft, it turned out that Eris is slightly smaller than Pluto and the largest mass of the trans-Neptunian objects known to date. Eris was discovered by a group of American astronomers using a 122-cm telescope located at the Palomar Observatory for observations. The statement about the discovery of Eris was published on 29.07.2005. The name of the Greek goddess of discord, Eris, was approved on 13.09.2006. The average distance of Eris from the Sun is about 68.05 AU. Its orbit is highly elongated, with an eccentricity of about 0.435. This value of the eccentricity of the Eris orbit significantly exceeds the value of the eccentricity for all classical Kuiper belt objects. The maximum distance of Eris from the Sun is about 97.6 AU, the minimum is 38.46 AU. Therefore, at perihelion, Eris is even closer to the Sun than Pluto is at aphelion. Eris began to approach the Sun after April 1977. Its orbit is inclined to the ecliptic plane at an angle of 43.82°. The value of the period of rotation of Eris around the Sun is 561 years. Therefore, it will reach the closest point of its orbit from the Sun only in 2258. Based on observations of the dwarf planet Eris's occultation of the very faint star USNO-A2 0825-00375767 in the constellation Cetus with an apparent magnitude of 17.1m, its diameter was determined to be 2326±12 km with an albedo of 0.96(+0.09−0.04). The mass of Eris was determined from the rotation of its satellite. It turned out to be almost a quarter larger than the mass of Pluto and equal to (1.67±0.02)⋅1022 kg. This gave an average density of Eris of 2.52±0.05 g/cm³. The inclination of the axis of rotation of Eris still remains unknown. Based on the analysis of data on the isotopic composition of methane present on the surface of Eris, it was concluded that it has signs of hydrothermal origin. Therefore, noticeable thermal activity should still be preserved in the bowels of this planet.