1867 Deiphobus is a dark

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 p ...

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 Trojan ...

, approximately in diameter. It was discovered on 3 March 1971, by Argentine astronomers Carlos Cesco and A. G. Samuel at the

Leoncito Astronomical Complex The El Leoncito Astronomical Complex (Spanish: Complejo Astronómico El Leoncito - CASLEO) is an astronomical observatory in the San Juan Province of Argentina. CASLEO is one of two observatories located within El Leoncito National Park, which ...

in Argentina, and later named after the Trojan prince

Deiphobus In Greek mythology, Deiphobus ( grc, , Dēḯphobos) was a son of Priam and Hecuba. He was a prince of Troy, and the greatest of Priam's sons after Hector and Paris. Deiphobus killed four men of fame in the Trojan War. Description Deiphobus ...

from Greek mythology. The dark

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

is one of the largest Jupiter trojans. It is a member of the Ennomos family and has a long

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 58.66 hours.

Orbit and classification

''Deiphobus'' is a dark Jovian

asteroid An asteroid is a minor planet of the Solar System#Inner solar system, 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 o ...

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 ...

, 60 ° behind its orbit in a 1:1 resonance . It is a member of the Ennomos family (

009 009 may refer to: * OO9, gauge model railways * O09, FAA identifier for Round Valley Airport * 0O9, FAA identifier for Ward Field, see List of airports in California * British secret agent 009, see 00 Agent * BA 009, see British Airways Flight 9 ...

), a small Jovian

asteroid family An asteroid family is a population of asteroids that share similar proper orbital elements, such as semimajor axis, eccentricity, and orbital inclination. The members of the families are thought to be fragments of past asteroid collisions. A ...

with 30 known members, named after

4709 Ennomos 4709 Ennomos is a large Jupiter trojan from the Trojan camp and the namesake of the small Ennomos family, approximately in diameter. It was discovered on 12 October 1988, by American astronomer Carolyn Shoemaker at the Palomar Observatory in ...

. There only a few Jovian families known to date. The Ennomos family was first identified by Jakub Rozehnal and Miroslav Brož in 2011. However, a different HCM-based analysis assigns ''Deiphobus'' to the Jovian background population. It orbits the Sun at a distance of 4.9–5.4 AU once every 11 years and 7 months (4,241 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 lo ...

of 5.13 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- center, in geometry * Eccentricity (graph theory) of a ...

of 0.04 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 27 ° with respect to the

ecliptic The ecliptic or ecliptic plane is the orbital plane of the Earth around the Sun. From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic agai ...

. 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 its official discovery observation at Leoncito in March 1971.

Physical characteristics

''Deiphobus'' is characterized as a dark

in the

Tholen Tholen () is a 25,000 people Municipalities of the Netherlands, 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 m ...

, Barucci, Tedesco, as well as in the SDSS-based taxonomy.

Lightcurves

Several rotational

lightcurve In astronomy, a light curve is a graph of light intensity of a celestial object or region as a function of time, typically with the magnitude of light received on the y axis and with time on the x axis. The light is usually in a particular frequ ...

have been obtained since 1987, when the first photometric observations of ''Deiphobus'' by Linda French at CTIO indicated that the body has longer-than average

of at least 24 hours.(). In February 1994, 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

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 located at the site and are partly maintained by ESO. The observatory is ...

La Silla Observatory 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 located at the site and are partly maintained by ESO. The observatory is ...

in Chile, gave a slow rotation period 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 ...

(). Since 2015, follow-up observations 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 natu ...

at the Center for Solar System Studies measured 58.62 and 58.699, confirming Mottola's long period (), and superseding other reported periods from fragmentary lightcurves (). While not being a slow rotator, ''Deiphobus'' has a much longer rotation period than the vast majority of asteroids, which typically rotate between 2 and 20 hours once around their axis. Among all large Jovian asteroids, only 617 Patroclus has a longer period than ''Deiphobus''.

Diameter and albedo

According to the surveys carried out by the Infrared Astronomical Satellite

IRAS The Infrared Astronomical Satellite ( Dutch: ''Infrarood Astronomische Satelliet'') (IRAS) was the first space telescope to perform a survey of the entire night sky at infrared wavelengths. Launched on 25 January 1983, its mission lasted ten mo ...

, the Japanese Akari satellite, and 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 2 ...

with its subsequent

NEOWISE 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 20 ...

mission, ''Deiphobus'' measures between 118.22 and 131.31 kilometers in diameter, and its surface has an

albedo Albedo (; ) is the measure of the diffuse reflection of 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 that refl ...

between 0.037 and 0.060. The ''Collaborative Asteroid Lightcurve Link'' derives an albedo of 0.0396 and a diameter of 122.65 kilometers based on an

absolute magnitude Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse logarithmic astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it we ...

of 8.68.

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 '' ...

was named after the Trojan warrior,

, son of King

Priam In Greek mythology, Priam (; grc-gre, Πρίαμος, ) was the legendary and last king of Troy during the Trojan War. He was the son of Laomedon. His many children included notable characters such as Hector, Paris, and Cassandra. Etymology ...

''(also see

108 Hecuba Hecuba (minor planet designation: 108 Hecuba) is a fairly large and bright main-belt asteroid. It was discovered by Karl Theodor Robert Luther on 2 April 1869, and named after Hecuba, wife of King Priam in the legends of the Trojan War in Greek My ...

and

884 Priamus 884 Priamus is a large Jupiter trojan from the Trojan camp, approximately in diameter. It was discovered on 22 September 1917, by German astronomer Max Wolf at Heidelberg Observatory in southern Germany. The dark D-type asteroid is one of the ...

)''. The official 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 20 February 1976 ().

Notes

References

External links

Long-term evolution of asteroid families among Jovian Trojans
Jakub Rozehnal and Miroslav Brož (2014)
Asteroid Lightcurve Database (LCDB)
query form

)
Dictionary of Minor Planet Names
Google books

– Minor Planet Center * * {{DEFAULTSORT:Deiphobus 001867 001867 Discoveries by Carlos Ulrrico Cesco Named minor planets 001867 19710303