, nicknamed ''Caju'', is an extreme

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). ...

from the

scattered disc The scattered disc (or scattered disk) is a distant circumstellar disc in the Solar System that is sparsely populated by icy small Solar System bodies, which are a subset of the broader family of trans-Neptunian objects. The scattered-disc obj ...

on a highly eccentric and inclined orbit in the outermost region 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 17 January 2015, by astronomers with the

Dark Energy Survey 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 ...

Cerro Tololo Observatory The Cerro Tololo Inter-American Observatory (CTIO) is an 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 the southeas ...

in Chile. It has been described as an extended scattered disc object (ESDO), and fits into the group of extreme objects that led to the prediction of

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 ...

, and has the highest

orbital 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 Earth ...

of any of these objects.

Orbit and classification

orbits the Sun at a distance of 35.2–821 AU once every 8856 years (3,234,488 days;

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 428 AU). Its orbit has an exceptionally 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 0.92 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 54 ° 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 ...

. This makes it a probable outlier among the known

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 ...

Planet Nine

fits into the group of extreme trans-Neptunian objects that originally led to the prediction of

. The group consists of more than a dozen bodies with a

perihelion An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides perta ...

greater than 30 AU and a semi-major axis greater than 250 AU, with having the highest

of any of these objects. Subsequently, unrefereed work by de la Fuente Marcos (2018) found that current orbital orientation in space is not easily explained by the same mechanism that keeps other extreme trans-Neptunian objects together, suggesting that the clustering in its orbital angles cannot be attributed to Planet Nine's influence. However, regardless of the current direction of its orbit, its high orbital inclination appears to fit into the class of high-semi major axis, high-inclination objects predicted by Batygin & Morbedelli (2017) to be generated by Planet Nine.

Discovery

The body's

observation arc In observational astronomy, the observation arc (or arc length) of a Solar System body is the time period between its earliest and latest observations, used for tracing the body's path. It is usually given in days or years. The term is mostly use ...

begins with a

precovery In astronomy, precovery (short for pre-discovery recovery) is the process of finding the image of a celestial object in images or photographic plates predating its discovery, typically for the purpose of calculating a more accurate orbit. This ha ...

taken on 27 November 2014 by astronomers with the

using the

DECam 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, and near-infrared to measure the expansion of the universe using Type Ia supernov ...

instrument of the

Víctor M. Blanco Telescope The Víctor M. Blanco Telescope, also known as the Blanco 4m, is a 4-metre aperture telescope located at the Cerro Tololo Inter-American Observatory, Chile on the summit of Mt. Cerro Tololo. Commissioned in 1974 and completed in 1976, the telescop ...

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. Its discovery was reported in a paper published by

astronomers in 2018.

Physical characteristics

According to Michael Brown and ''Johnston's Archive'', measures 524 and 584 kilometers in diameter based on an 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 ...

of 0.08 and 0.09, respectively. As of 2018, no rotational

lightcurve In astronomy, a light curve is a graph (discrete mathematics), graph of the Radiance, light intensity of a celestial object or region as a function of time, typically with the magnitude (astronomy), magnitude of light received on the ''y''-axis ...

of has been obtained from photometric observations. The body's

rotation period In astronomy, the rotation period or spin period of a celestial object (e.g., star, planet, moon, asteroid) has two definitions. The first one corresponds to the '' sidereal rotation period'' (or ''sidereal day''), i.e., the time that the objec ...

, pole and shape remain unknown.

Notes

References

External links

Discovery and Dynamical Analysis of an Extreme Trans-Neptunian Object with a High Orbital Inclination
14 May 2018
A New World's Extraordinary Orbit Points to Planet Nine
15 May 2018 * * {{DEFAULTSORT:768325 Scattered disc and detached objects Extreme trans-Neptunian objects Discoveries by OSSOS 20151127 Inner Oort cloud