6002 Eetion, ''

provisional designation Provisional designation in astronomy is the naming convention applied to astronomical objects immediately following their discovery. The provisional designation is usually superseded by a permanent designation once a reliable orbit has been calcu ...

'': , is a mid-sized

Jupiter trojan The Jupiter trojans, commonly called trojan asteroids or simply trojans, are a large group of asteroids that share the planet Jupiter's orbit around the Sun. Relative to Jupiter, each Trojan (celestial body), trojan Libration point orbit, librat ...

from the

Trojan camp This is a list of Jupiter trojans that lie in the Trojan camp, an elongated curved region around the trailing Lagrangian point, 60° behind Jupiter in its orbit. All the asteroids at the trailing point have names corresponding to participants ...

, approximately in diameter. It was discovered by Poul Jensen at the

Brorfelde Observatory Brorfelde Observatory (; List of observatory codes, obs. code: IAU code#054, 054) is an astronomy, astronomical observatory located in Brorfelde near Holbæk, Denmark. It is home to the Brorfelde Schmidt Telescope and was run as a branch ...

in 1988, and has not been named since its

numbering There are many different numbering schemes for assigning nominal numbers to entities. These generally require an agreed set of rules, or a central coordinator. The schemes can be considered to be examples of a primary key In the relational model ...

in June 1994. The dark Jovian

asteroid An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...

has a

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 ...

of 12.9 hours. In 2021, it was named from Greek mythology after King

Eetion In Greek mythology, Eëtion or Eetion (; ) is the king of the Anatolian city of Cilician Thebe. He is said to be the father of Andromache, the wife of the Trojan prince Hector. In the sixth book of the ''Iliad'', Andromache tells her husband t ...

, who was killed by

Achilles In Greek mythology, Achilles ( ) or Achilleus () was a hero of the Trojan War who was known as being the greatest of all the Greek warriors. The central character in Homer's ''Iliad'', he was the son of the Nereids, Nereid Thetis and Peleus, ...

during the raid on Thebe.

Discovery

''Eetion'' discovered on 8 September 1988, by Danish astronomer Poul Jensen at the

near Holbæk, Denmark, who on very same night also discovered the Jupiter trojan , and several other

main-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 ...

asteroids including , , , , and .

Orbit and classification

''Eetion'' is a dark Jovian

in a 1:1

orbital resonance In celestial mechanics, orbital resonance occurs when orbiting bodies exert regular, periodic gravitational influence on each other, usually because their orbital periods are related by a ratio of small integers. Most commonly, this relation ...

with Jupiter. It is located in the trailering

at the Gas Giant's

Lagrangian point In celestial mechanics, the Lagrange points (; also Lagrangian points or libration points) are points of equilibrium (mechanics), equilibrium for small-mass objects under the gravity, gravitational influence of two massive orbit, orbiting b ...

, 60 ° behind its orbit . It is also a non-

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

asteroid of the Jovian background population. It orbits the Sun at a distance of 4.7–5.7 AU once every 11 years and 11 months (4,361 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 5.22 AU). Its orbit has an

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 0.09 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 16 ° 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 ...

. A first

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 ...

was taken at

Palomar Observatory The Palomar Observatory is an astronomical research observatory in the Palomar Mountains of San Diego County, California, United States. It is owned and operated by the California Institute of Technology (Caltech). Research time at the observat ...

in September 1953, extending 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 ...

by 35 years prior to its official discovery observation at Brorfelde.

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 numbered 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 23 June 1994 (). On 29 November 2021, IAU's

Working Group for Small Bodies Nomenclature In ancient times, only the Sun and Moon, a few stars, and the most easily visible planets had names. Over the last few hundred years, the number of identified astronomical objects has risen from hundreds to over a billion, and more are discovered e ...

it from Greek mythology after King

of Thebe Hypoplakia, father of

Andromache In Greek mythology, Andromache (; , ) was the wife of Hector, daughter of Eetion, and sister to Podes. She was born and raised in the city of Cilician Thebe, over which her father ruled. The name means "man battler", "fighter of men" or "m ...

, and father-in-law of

Hector In Greek mythology, Hector (; , ) was a Trojan prince, a hero and the greatest warrior for Troy during the Trojan War. He is a major character in Homer's ''Iliad'', where he leads the Trojans and their allies in the defense of Troy, killing c ...

. Eetion was killed during the raid on Thebe by

Physical characteristics

This Jupiter trojan is an assumed, carbonaceous

C-type asteroid C-type (carbonaceous ) asteroids are the most common variety, forming around 75% of known asteroids. They are volatile-rich and distinguished by a very low albedo because their composition includes a large amount of carbon, in addition to rocks ...

Rotation period

In February 1993, ''Eetion'' was observed by astronomers Stefano Mottola and Mario Di Martino with the

ESO 1-metre telescope La Silla Observatory is an astronomical observatory in Chile with three telescopes built and operated by the European Southern Observatory (ESO). Several other telescopes are also located at the site and are partly maintained by ESO. The observato ...

and its DLR MkII CCD-camera at La Silla in Chile. The photometric observations were used to build a

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 ...

showing a

of hours with a brightness variation of

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 ...

(). It was the body's first determined rotation period in literature.

Diameter and albedo

According to the survey carried out by NASA's

Wide-field Infrared Survey Explorer Wide-field Infrared Survey Explorer (WISE, List of observatory codes, observatory code C51, Explorer 92 and MIDEX-6) was a NASA infrared astronomy Space observatory, space telescope in the Explorers Program launched in December 2009.. . WISE L ...

with its subsequent

NEOWISE Wide-field Infrared Survey Explorer (WISE, observatory code C51, Explorer 92 and MIDEX-6) was a NASA infrared astronomy space telescope in the Explorers Program launched in December 2009.. . WISE discovered thousands of minor planets and nu ...

mission, ''Eetion'' measures 40.4 kilometers in diameter and its surface has an

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 0.075, while the ''Collaborative Asteroid Lightcurve Link'' assumes a standard albedo for a carbonaceous asteroid of 0.057 and calculates a diameter of 42.23 kilometers, based on an absolute magnitude of 10.6.

References

External links

Asteroid Lightcurve Database (LCDB)
query form

)

– Minor Planet Center
Asteroid (6002) 1988 RO
at the Small Bodies Data Ferret * * {{DEFAULTSORT:Eetion 006002 Discoveries by Poul Jensen (astronomer) Named minor planets 19880908