2241 Alcathous is a large

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

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. All the asteroids at the trailing point have names corresponding to participants on the Troj ...

, approximately in diameter. It was discovered on 22 November 1979, by American astronomer

Charles Kowal Charles Thomas Kowal (November 8, 1940 – November 28, 2011) was an American astronomer known for his observations and discoveries in the Solar System. As a staff astronomer at Caltech's Mount Wilson and Palomar Mountain observatories between ...

at the

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 southern California, United States. The dark

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 ...

belongs to the 20 largest Jupiter trojans and 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 7.7 hours. It was named after Alcathous from Greek mythology.

Orbit and classification

''Alcathous'' is a 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. ...

orbiting in the trailing

at Jupiter'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 ° behind its orbit in a 1:1 resonance . It is also a non- family asteroid of the Jovian background population. It orbits the Sun at a distance of 4.8–5.5 AU once every 11 years and 10 months (4,309 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 5.18 AU). Its orbit has an eccentricity of 0.07 and an inclination of 17 ° with respect to the ecliptic. The body's observation arc 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 in June 1950, more than 29 years prior to its official discovery observation.

Physical characteristics

In the

Tholen Tholen () is a 25,000 people municipality in the southwest of the Netherlands. The municipality of Tholen takes its name from the town of Tholen, which is the largest population center in the municipality. The municipality consists of two peninsu ...

, Barucci and Tedesco taxonomy, ''Alcathous'' is classified as a dark

. It is the 8th largest of all 46 D-type asteroids in the Tholen classification.

Rotation period

A large number rotational lightcurves have been obtained since December 1991, when ''Alcathous'' was first observed by

Stefano Mottola This is a list of minor-planet discoverers credited by the Minor Planet Center with the discovery of one or several minor planets (such as near-Earth and main-belt asteroids, Jupiter trojans and distant objects). , the discovery of 612,011 numb ...

with the Loiano 1.52-meter telescope at Bologna Observatory, Italy. In 1994, the asteroid's

was also measured by

Giovanni de Sanctis Giovanni de Sanctis (born 1949) is an Italian astronomer and discoverer of minor planets at the Osservatorio Astronomico di Torino (Astronomical Observatory of Turin) in Turin, Italy. His name is sometimes spelt DeSanctis, particularly in the Mi ...

and collaborators (). Several photometric observations between 2010 and 2017, by Daniel Coley and

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 ...

and at GMARS , also include the so-far best-rated period of 7.689 hours with a brightness amplitude of 0.22 magnitude ().

Diameter and albedo

According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, ''Alcathous'' measures between 113.68 and 118.87 kilometers in diameter and its surface has an albedo between 0.044 and 0.048. The ''Collaborative Asteroid Lightcurve Link'' adopts the results obtained by IRAS, that is, an albedo of 0.0471 and a diameter of 114.63 kilometers based on an absolute magnitude of 8.64.

Naming

This minor planet was named after Alcathous, brave and handsome Trojan leader in Homer's '' Iliad''. Alcathous was the husband of

Hippodamia Hippodamia (, ; also Hippodamea and Hippodameia; Ancient Greek: Ἱπποδάμεια "she who masters horses" derived from ''hippos'' "horse" and ''damazein'' "to tame") was a Greek mythological figure. She was the queen of Pisa as the wife ...

the eldest daughter of Anchises ''(also see )'', who excelled all other girls of her age in beauty, skill and wit. Alcathous, previously uninjured in the Trojan War, was struck by Poseidon ''(also see )'' with blindness and paralysis and was killed easily by a spear thrown by the Greek general and Cretan commander, Idomeneus ''(also see )''. 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 10 November 1992 ().

Notes

References

External links

Asteroid Lightcurve Database (LCDB)
query form

)
Dictionary of Minor Planet Names
Google books

– Minor Planet Center * * {{DEFAULTSORT:Alcathous 002241 Discoveries by Charles T. Kowal Named minor planets 002241 19791122