 | |
| Discovery[1][2] | |
|---|---|
| Discovered by | D. J. Tholen C. Trujillo S. S. Sheppard |
| Discovery site | Mauna Kea Obs. |
| Discovery date | 13 October 2015 |
| Designations | |
| (541132) Leleākūhonua | |
| Pronunciation | English:/ˌlɛleɪɑːˌkuːhoʊˈnuːə/ Hawaiian:[lelejaːkuːhoˈnuwə] |
| TNO[5] · sednoid[6][7] | |
| Orbital characteristics (barycentric)[8] | |
| Epoch 25 February 2023 (JD 2460000.5) | |
| Uncertainty parameter 3[1] | |
| Observation arc | 13.04 yr (4,763 d)[1] |
| Earliestprecovery date | 5 October 2005[1] |
| Aphelion | 2114 AU |
| Perihelion | 64.95 AU |
| 1193 AU | |
| Eccentricity | 0.94572 |
| 41222 yr | |
| 359.515° | |
| 0° 0m 0.086s / day | |
| Inclination | 11.671° |
| 300.989° | |
| ≈ 11 June 2078[9] ±4.5 months | |
| 118.236° | |
| Knownsatellites | 0 |
| Physical characteristics | |
| 110+14 −10 km[10] | |
| 0.21+0.03 −0.05[10] | |
| 24.5[11] | |
| 5.57±0.13[5] | |
541132 Leleākūhonua (/ˌlɛleɪɑːˌkuːhoʊˈnuːə/;provisional designation2015 TG387) is anextreme trans-Neptunian object andsednoid in the outermost part of theSolar System. It was first observed on 13 October 2015, by astronomers at theMauna Kea Observatories, Hawaii. Based on its discovery date nearHalloween and the letters in its provisional designation2015 TG387, the object was informally nicknamed "The Goblin" by its discoverers[4] and later named Leleākūhonua, comparing its orbit to the flight of thePacific golden plover. It was the third sednoid discovered, afterSedna and2012 VP113, and measures around 220 kilometers (140 miles) in diameter.[10]
Leleākūhonua was first observed on 13 October 2015 at theMauna Kea Observatory (T09), by American astronomersDavid Tholen,Chad Trujillo andScott Sheppard during theirastronomical survey for objects located beyond theKuiper Cliff.[1][2] The unofficial discovery was publicly announced on 1 October 2018.[2][12] The survey uses two principal telescopes: For the Northern hemisphere, the 8.2-meterSubaru Telescope with itsHyper Suprime Camera atMauna Kea Observatories, Hawaii, and for the Southern hemisphere, the 4-meterBlanco Telescope and itsDark Energy Camera atCerro Tololo Inter-American Observatory in Chile. For follow-up observations to determine an object's orbit, the astronomers are using theMagellan and theLowell Discovery telescopes. The survey's discoveries include2012 VP113,2014 SR349 and2013 FT28.[6]
Leleākūhonua orbits the Sun at a distance varying from 65 to about 2800 AU once roughly every 55,000 years (semi-major axis of around 1450 AU). Its orbit has a very higheccentricity of 0.955 and aninclination of12° with respect to theecliptic.[5] It belongs to theextreme trans-Neptunian objects defined by their large semi-major axis and is the third sednoid ever to be discovered, afterSedna and2012 VP113 ("Biden").
Along with the similar orbits of other distanttrans-Neptunian objects, the orbit of Leleākūhonua suggests, but does not prove, the existence ofPlanet Nine in the outer Solar System.[6][13]
As of 2019[update], the object is inbound 78 AU from the Sun;[11] about two-and-a-half times farther out than Pluto's current location.[14] It will come to perihelion (closest approach to the Sun) in 2078.[5] As with Sedna, it would not have been found had it not been on the inner leg of its long orbit. This suggests that there may be many similar objects, most too distant to be detected by contemporary technological methods. Following the discovery of Leleākūhonua, Sheppard et al. concluded that it implies a population of about 2 millioninner Oort cloud objects larger than 40 km (25 mi), with a combined total mass of1×1022 kg, about the mass of Pluto (a fraction the mass of Earth's moon but several times the mass of theasteroid belt).[6]
Thisminor planet wasnumbered by theMinor Planet Center on 10 October 2019 (M.P.C. 117077).[15] In June 2020, it was formally named Leleākūhonua 'it flies until land appears' (lele 'to fly' +ā 'until' +kū 'to appear' +honua 'land').[16][17] The name was suggested by students in the Hawaiian-language program A Hua He Inoa. The object reminded students of the migrations of thekolea, orPacific golden plover, which migrates from Alaska to Hawaii.[18] The English description states that the name "compares the orbit to the flight of migratory birds and evokes a yearning to be near Earth" (in Hawaiian,me he manu i ke ala pōʻaiapuni lā, he paʻa mau nō ia i ka hui me kona pūnana i kumu mai ai – like a bird on a path circling the sun, it is forever seeking a leeward wind back toward home.)[1][19]
The size of Leleākūhonua depends on the assumedalbedo (reflectivity); if it is a darker object then it would also have to be larger; a higher albedo would demand that it be smaller.[20] The faint object has a visualmagnitude of 24.64, comparable to the visual magnitudes ofPluto's smaller moons.[11][20] It was initially estimated to be 300 km (190 mi) in diameter under the assumption of an albedo of 0.15,[6] though observations of a single-chordstellar occultation atPenticton, Canada on 20 October 2018 suggested a smaller diameter of 220 km (140 mi), corresponding to a higher albedo of 0.21.[10]
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