3801 Thrasymedes 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 librates around one of Jupiter's stable Lagrange poin ...

from the

Greek camp This is a list of Jupiter trojans that lie in the Greek camp, an elongated curved region around the leading Lagrangian point (), 60 ° ahead of Jupiter in its orbit. All the asteroids at Jupiter's point have names corresponding to participants ...

, approximately in diameter. It was discovered on 6 November 1985, by astronomers with the Spacewatch survey at the Kitt Peak National Observatory in Arizona, United States. The dark Jovian

asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...

has a

rotation period The rotation period of a celestial object (e.g., star, gas giant, planet, moon, asteroid) may refer to its sidereal rotation period, i.e. the time that the object takes to complete a single revolution around its axis of rotation relative to the ...

of 20.3 hours and forms an

asteroid pair An asteroid pair, or (if more than one body) an asteroid cluster, are asteroids which at some point in the past had very small relative velocities, and are typically formed either by a collisional break-up of a parent body, or from binary asteroids ...

with

1583 Antilochus 1583 Antilochus is a large Jupiter trojan from the Greek camp, approximately in diameter. It was discovered on 19 September 1950, by Belgian astronomer Sylvain Arend at Uccle Observatory in Belgium, and later named after the hero Antilochus fr ...

. It was named after

Thrasymedes Thrasymedes of Paros ( el, Θρασυμήδης ο Παριανός) was an ancient Greek sculptor. Formerly he was regarded as a pupil of Phidias because he set up in the temple of Asclepius at Epidaurus a seated statue of that deity made of iv ...

from Greek mythology.

Orbit and classification

''Thrasymedes'' is a dark Jovian

in a 1:1 orbital resonance with Jupiter. It is located in the leading

at the Gas Giant's

Lagrangian point In celestial mechanics, the Lagrange points (; also Lagrangian points or libration points) are points of equilibrium for small-mass objects under the influence of two massive orbiting bodies. Mathematically, this involves the solution of th ...

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

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

asteroid of the Jovian background population. It orbits the Sun at a distance of 5.2–5.4 AU once every 12 years and 3 months (4,486 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 long ...

of 5.32 AU). Its orbit has an eccentricity of 0.02 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 Plane of reference, reference plane and the orbital plane or Axis of rotation, axis of direction of the orbiting object ...

of 28 ° with respect to the ecliptic. 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 an object in images or photographic plates predating its discovery, typically for the purpose of calculating a more accurate orbit. This happens mos ...

taken at

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

in April 1954, more than 31 years prior to its official discovery observation at Kitt Peak.

Asteroid pair

In 1993, Andrea Milani suggested that ''Thrasymedes'' forms an

with 1583 Antilochus, using the hierarchical clustering method (HCM), which looks for groupings of neighboring asteroids based on the smallest distances between them in the

proper orbital element __NOTOC__ The proper orbital elements or proper elements of an orbit are constants of motion of an object in space that remain practically unchanged over an astronomically long timescale. The term is usually used to describe the three quantitie ...

space. The astronomer describes the finding as statistically significant though difficult to account for by a regular collisional event. The Antilochus–Thrasymedes pair is not listed at the Johnston's archive.

Physical characteristics

''Thrasymedes'' is an assumed, carbonaceous C-type asteroid, while the majority of larger Jupiter trojans are

D-type asteroid D-type asteroids have a very low albedo and a featureless reddish Asteroid spectral types, spectrum. It has been suggested that they have a composition of organic-rich silicates, carbon and anhydrous silicates, possibly with water ice in their inte ...

Rotation period

The first two fragmentary rotational lightcurves of ''Thrasymedes'', taken before 2015, gave a

of 9.60 and 16.02 hours, respectively (). In 2015, photometric observations by the ''Kepler'' space telescope gave two lightcurves. The best-rated one showed a period of hours and a brightness variation of 0.14 magnitude (). In June 2016, another period determination from 16 nights of observation by

Robert Stephens Sir Robert Graham Stephens (14 July 193112 November 1995) was a leading English actor in the early years of Britain's Royal National Theatre. He was one of the most respected actors of his generation and was at one time regarded as the natur ...

at the

Center for Solar System Studies This is a list of observatory codes (IAU codes or MPC codes) published by the Minor Planet Center. For a detailed description, ''see observations of small Solar System bodies''. List References * {{DEFAULTSORT:Observat ...

in California gave a divergent hours with a notably large amplitude of 1.07 magnitude ().

Diameter and albedo

According to the survey carried out by the NEOWISE mission of NASA's

Wide-field Infrared Survey Explorer Wide-field Infrared Survey Explorer (WISE, observatory code C51, Explorer 92 and SMEX-6) is a NASA infrared astronomy space telescope in the Explorers Program. It was launched in December 2009, and placed in hibernation mode in February 2011, ...

, ''Thrasymedes'' measures 34.28 kilometers in diameter and its surface has an

albedo Albedo (; ) is the measure of the diffuse reflection of sunlight, solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body ...

of 0.066, while he ''Collaborative Asteroid Lightcurve Link'' assumes a standard albedo for a carbonaceous asteroid of 0.057 and calculates a diameter of 35.12 kilometers based on an

absolute magnitude Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse Logarithmic scale, logarithmic Magnitude (astronomy), astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent mag ...

of 11.0.

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 named after the Greek warrior

, commander of 15 ships to Troy. He is the son of

Nestor Nestor may refer to: * Nestor (mythology), King of Pylos in Greek mythology Arts and entertainment * "Nestor" (''Ulysses'' episode) an episode in James Joyce's novel ''Ulysses'' * Nestor Studios, first-ever motion picture studio in Hollywood, L ...

and brother of

Antilochus In Greek mythology, Antilochus (; Ancient Greek: Ἀντίλοχος ''Antílokhos'') was a prince of Pylos and one of the Achaeans in the Trojan War. Family Antilochus was the son of King Nestor either by Anaxibia or Eurydice. He was the brot ...

, who was killed during a fight with

Memnon In Greek mythology, Memnon (; Ancient Greek: Μέμνων means 'resolute') was a king of Aethiopia and son of Tithonus and Eos. As a warrior he was considered to be almost Achilles' equal in skill. During the Trojan War, he brought an army t ...

. He was also one of the 30 warriors to enter the wooden

Trojan Horse The Trojan Horse was a wooden horse said to have been used by the Greeks during the Trojan War to enter the city of Troy and win the war. The Trojan Horse is not mentioned in Homer's ''Iliad'', with the poem ending before the war is concluded, ...

. The official naming citation was published 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. Function ...

on 31 May 1988 (). The citation also mentions that this Jovian asteroids may have a common origin with 1583 Antilochus, because their orbits are very similar.

Orbit and classification

Asteroid pair

Physical characteristics

Rotation period

Diameter and albedo

Naming

Notes

References

External links