4057 Demophon is a larger

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 15 October 1985 by American astronomer Edward Bowell at the Anderson Mesa Station of the

Lowell Observatory Lowell Observatory is an astronomical observatory in Flagstaff, Arizona, United States. Lowell Observatory was established in 1894, placing it among the oldest observatories in the United States, and was designated a National Historic Landmark ...

near Flagstaff, Arizona. 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 longer-than-average

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 29.8 hours. It was named after the Athen prince Demophon who fought in the Trojan War.

Orbit and classification

''Demophon'' 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 asteroid of the Jovian background population. It orbits the Sun at a distance of 4.6–5.9 AU once every 12 years and 1 month (4,410 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 5.26 AU). Its orbit has an eccentricity of 0.12 and an inclination of 3 ° 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 Crimea–Nauchnij in September 1985, just three weeks prior to its official discovery observation at Anderson Mesa.

Physical characteristics

''Demophon'' is an assumed, carbonaceous C-type asteroid. It has a high V–I color index of 1.06. Most larger Jupiter trojans are D-type asteroids.

Rotation period

In June 1994, a first rotational lightcurve of ''Demophon'' was obtained from photometric observations 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 ...

and Anders Erikson using the Dutch 0.9-metre Telescope at ESO's La Silla Observatory in Chile. Lightcurve analysis gave a

of 29.31 hours with a brightness variation of 0.23 magnitude (). In August 2015, photometric observations by the Kepler space telescope rendered another two lightcurves (). The best-rated one showed a period of hours and a brightness variation of 0.21 magnitude. Most asteroids have a shorter rotation period between 2 and 20 hours ''(also see List of slow rotators)''.

Diameter and albedo

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, ''Demophon'' measures 45.68 kilometers in diameter and its surface has an albedo of 0.077, while the ''Collaborative Asteroid Lightcurve Link'' assumes a standard albedo for a carbonaceous asteroid of 0.057 and calculates a diameter of 53.16 kilometers based on an absolute magnitude of 10.1.

Naming

This minor planet was named from Greek mythology after the Athen prince Demophon, son of King Theseus and Phaedra. After participation in the Trojan War, Demophon married Phyllis, who committed suicide after he had abandoned her. 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 22 April 1997 ().

Orbit and classification

Physical characteristics

Rotation period

Diameter and albedo

Naming

References

External links