541132 Leleākūhonua
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541132 Leleākūhonua () ( provisional designation ) is an
extreme trans-Neptunian object An extreme trans-Neptunian object (ETNO) is a trans-Neptunian object orbiting the Sun well beyond Neptune (30  AU) in the outermost region of the Solar System. An ETNO has a large semi-major axis of at least 150–250 AU. The orbits of ET ...
and sednoid in the outermost part of the
Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...
. It was first observed on 13 October 2015, by astronomers at the
Mauna Kea Observatories The Mauna Kea Observatories (MKO) are a group of independent astronomical research facilities and large telescope observatories that are located at the summit of Mauna Kea on Hawaii (island), Hawaiʻi, United States. The facilities are located i ...
, Hawaii. Based on its discovery date near
Halloween Halloween, or Hallowe'en (less commonly known as Allhalloween, All Hallows' Eve, or All Saints' Eve), is a celebration geography of Halloween, observed in many countries on 31 October, the eve of the Western Christianity, Western Christian f ...
and the letters in its provisional designation , the object was informally nicknamed "The Goblin" by its discoverers and later named Leleākūhonua, comparing its orbit to the flight of the Pacific golden plover. It was the third sednoid discovered, after and , and measures around in diameter.


Discovery

Leleākūhonua was first observed on 13 October 2015 at the Mauna Kea Observatory , by American astronomers David Tholen, Chad Trujillo and Scott Sheppard during their
astronomical survey An astronomical survey is a general celestial cartography, map or astrophotography, image of a region of the sky (or of the whole sky) that lacks a specific observational target. Alternatively, an astronomical survey may comprise a set of image ...
for objects located beyond the
Kuiper Cliff The Kuiper belt ( ) is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical units (AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger—20 times ...
. The unofficial discovery was publicly announced on 1 October 2018. The survey uses two principal telescopes: For the Northern hemisphere, the 8.2-meter
Subaru Telescope is the telescope of the National Astronomical Observatory of Japan, located at the Mauna Kea Observatory on Hawaii. It is named after the open star cluster known in English as the Pleiades. It had the largest monolithic primary mirror in the ...
with its Hyper Suprime Camera at
Mauna Kea Observatories The Mauna Kea Observatories (MKO) are a group of independent astronomical research facilities and large telescope observatories that are located at the summit of Mauna Kea on Hawaii (island), Hawaiʻi, United States. The facilities are located i ...
, Hawaii, and for the Southern hemisphere, the 4-meter
Blanco Telescope Blanco (''white'' or ''blank'' in Spanish) or Los Blancos may refer to: People *Blanco (surname) Fictional characters *Blanco, a hobbit in J. R. R. Tolkien's Middle-earth *Blanco Webb, character in the BBC sitcom ''Porridge'' *Graboid#El Blanco, ...
and its
Dark Energy Camera The Dark Energy Survey (DES) is an astronomical survey designed to constrain the properties of dark energy. It uses images taken in the near-ultraviolet, Visible spectrum, visible, and near-infrared to measure the expansion of the universe using ...
at
Cerro Tololo Inter-American Observatory The Cerro Tololo Inter-American Observatory (CTIO) is an Astronomy, astronomical observatory located on the summit of Mt. Cerro Tololo in the Coquimbo Region of northern Chile, with additional facilities located on Mt. Cerro Pachón about to th ...
in Chile. For follow-up observations to determine an object's orbit, the astronomers are using the Magellan and the Lowell Discovery telescopes. The survey's discoveries include , and .


Orbit and classification

Leleākūhonua orbits the Sun at a distance varying from 65 to about 2000 AU once roughly every 32,000 years (
semi-major axis In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the longe ...
of around 1000–1200 AU). Its orbit has a very high
eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-Centre (geometry), center, in geometry * Eccentricity (g ...
of 0.94 and an
inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...
of with respect to the
ecliptic The ecliptic or ecliptic plane is the orbital plane of Earth's orbit, Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making. Fr ...
. It belongs to the
extreme trans-Neptunian object An extreme trans-Neptunian object (ETNO) is a trans-Neptunian object orbiting the Sun well beyond Neptune (30  AU) in the outermost region of the Solar System. An ETNO has a large semi-major axis of at least 150–250 AU. The orbits of ET ...
s defined by their large semi-major axis and is the third sednoid ever to be discovered, after and ("Biden").


Implications of orbit

Along with the similar orbits of other distant
trans-Neptunian object A trans-Neptunian object (TNO), also written transneptunian object, is any minor planet in the Solar System that orbits the Sun at a greater average distance than Neptune, which has an orbital semi-major axis of 30.1 astronomical units (AU). ...
s, the orbit of Leleākūhonua suggests, but does not prove, the existence of a hypothetical
Planet Nine Planet Nine is a List of hypothetical Solar System objects, hypothetical ninth planet in the outer region of the Solar System. Its gravitational effects could explain the peculiar clustering of orbits for a group of extreme trans-Neptunian obj ...
in the outer Solar System. , the object is inbound 78 AU from the Sun; about two-and-a-half times farther out than Pluto's current location. It will come to perihelion (closest approach to the Sun) in 2078. 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 million inner Oort cloud objects larger than , with a combined total mass of , about the mass of Pluto (a fraction the mass of Earth's moon but several times the mass of the
asteroid belt The asteroid belt is a torus-shaped region in the Solar System, centered on the Sun and roughly spanning the space between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies called asteroids ...
).


Numbering and naming

This
minor planet According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor ...
was by the
Minor Planet Center The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. Funct ...
on 10 October 2019 (). In June 2020, it was formally named Leleākūhonua 'it flies until land appears'. The name was suggested by students in the Hawaiian-language program A Hua He Inoa. The object reminded students of the migrations of the ''kolea'', or Pacific golden plover, which migrates from Alaska to Hawaii.Meghan Bartels
'The Goblin' dwarf planet and an ancient quasar receive Hawaiian names
Space.com, July 01, 2020
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 pōaiapuni lā, he paa 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.)


Physical characteristics

The size of Leleākūhonua depends on the assumed
albedo Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...
(reflectivity); if it is a darker object then it would also have to be larger; a higher albedo would demand that it be smaller. The faint object has a visual
magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...
of 24.64, comparable to the visual magnitudes of Pluto's smaller moons. It was initially estimated to be in diameter under the assumption of an albedo of 0.15, though observations of a single-chord
stellar occultation Stellar means anything related to one or more stars (''stella''). The term may also refer to: Arts, entertainment, and media * Stellar (magazine), ''Stellar'' (magazine), an Irish lifestyle and fashion magazine * Stellar Loussier, a character fro ...
at Penticton, Canada on 20 October 2018 suggested a smaller diameter of , corresponding to a higher albedo of 0.21.


Visualizations

2015_TG387_hoverview.png, Simulated view of Solar System as seen from Leleākūhonua, showing the orbits of major planets and positions of other extreme
Trans-Neptunian objects A trans-Neptunian object (TNO), also written transneptunian object, is any minor planet in the Solar System that orbits the Sun at a greater average distance than Neptune, which has an orbital semi-major axis of 30.1 astronomical units (AU). T ...
. File:2015 TG387-sky-retropath.png, View of Leleākūhonua from Earth, showing retrograde loops every year, with current position near γ Pegasi


See also

*
List of Solar System objects most distant from the Sun These Solar System minor planets are the furthest from the Sun . The objects have been categorized by their approximate current distance from the Sun, and not by the calculated aphelion of their orbit. The list changes over time because the obj ...
* List of Solar System objects by greatest aphelion * V774104


References


External links


List Of Centaurs and Scattered-Disk Objects
''Minor Planet Center'' * * {{DEFAULTSORT:Leleakuhonua L 541132 Discoveries by David J. Tholen Discoveries by Chad Trujillo Named minor planets 541132 20151013 Inner Oort cloud