|Discovery date||17 March 2013|
(announced on 31 March 2014)
|Epoch 31 May 2020 (JD 2458900.5)|
|Uncertainty parameter 4|
|Observation arc||2585 days (7.08 yr)|
|Earliest precovery date||15 March 2011 (Pan-STARRS)|
|Aphelion||82.07455 AU (12.278178 Tm)|
|Perihelion||35.24656 AU (5.272810 Tm)|
|58.66055 AU (8.775493 Tm)|
|449.29 yr (164,103 d)|
|0° 0m 7.897s /day|
|≈ November 2202|
−85 km (effective diameter)
−83 km (primary)[a]
(532037) 2013 FY27 is a trans-Neptunian object and binary system that belongs to the scattered disc (like Eris). Its discovery was announced on 31 March 2014. It has an absolute magnitude (H) of 3.2. 2013 FY27 is a binary object, with two components approximately 740 kilometres (460 mi) and 190 kilometres (120 mi) in diameter. It is the ninth-intrinsically-brightest known trans-Neptunian object, and is approximately tied with 2002 AW197 and 2002 MS4 (to within measurement uncertainties) as the largest unnamed object in the Solar System.
2013 FY27 orbits the Sun once every 449 years. It will come to perihelion around November 2202,[b] at a distance of about 35.6 AU. It is currently near aphelion, 80 AU from the Sun, and, as a result, it has an apparent magnitude of 22. Its orbit has a significant inclination of 33°. The sednoid 2012 VP113 and the scattered-disc object 2013 FZ27 were discovered by the same survey as 2013 FY27 and were announced within about a week of one another.
2013 FY27 has a diameter of about 740 kilometres (460 mi), placing it at a transition zone between medium-sized and large TNOs. Using the Atacama Large Millimeter Array and Magellan Telescopes, its albedo was found to be 0.17, and its colour to be moderately red. 2013 FY27 is one of the largest moderately red TNOs. The physical processes that lead to a lack of such moderately red TNOs larger than 800 kilometres (500 mi) are not yet well understood.
The brightness of 2013 FY27 varies by less than 0.06 mag over hours and days, suggesting that it either has a very long rotation period, an approximately spheroidal shape, or a rotation axis pointing towards Earth.
Brown estimated, prior to the discovery of its satellite, that 2013 FY27 was very likely to be a dwarf planet, due to its large size. However, Grundy et al. calculate that bodies such as 2013 FY27, less than about 1000 km in diameter, with albedos less than ≈0.2 and densities of ≈1.2 g/cm3 or less, may retain a degree of porosity in their physical structure, having never collapsed into fully solid bodies.
Using Hubble Space Telescope observations taken in January 2018, Scott Sheppard found a satellite around 2013 FY27, 0.17 arcseconds away and 3.0±0.2 mag fainter than the primary. The discovery was announced on 10 August 2018. Assuming the two components have equal albedos, they are about 740 kilometres (460 mi) and 190 kilometres (120 mi) in diameter, respectively. Follow up observations were taken between May and July 2018 in order to determine the orbit of the satellite, but the results of those observations have not yet been released. Once the orbit is known, the mass of the system can be determined.