12929 Periboea, ''provisional designation'': , 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 poin ...

from the Trojan camp, approximately in diameter. It was discovered on 2 October 1999, by American astronomer

Charles W. Juels Charles W. Juels (1944 – January 21, 2009) was an American amateur astronomer and psychiatrist by profession, who became a prolific discoverer of minor planets after his retirement. Juels was born in New York City in 1944, and grew up in Cinc ...

at the Fountain Hills Observatory in Arizona. Originally considered a

centaur A centaur ( ; grc, κένταυρος, kéntauros; ), or occasionally hippocentaur, is a creature from Greek mythology with the upper body of a human and the lower body and legs of a horse. Centaurs are thought of in many Greek myths as being ...

, this now re-classified 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 9.3 hours and belongs to the 80 largest Jupiter trojans. It was named from Greek mythology after

Periboea __NOTOC__ In Greek mythology, the name Periboea (; Ancient Greek: Περίβοια "surrounded by cattle" derived from ''peri'' "around" and ''boes'' "cattle") refers to multiple figures: *Periboea, one of the 3,000 Oceanids, water-nymph daughte ...

, mother of Pelagon by the river-god Axius.

Orbit and classification

''Periboea'' is a dark Jovian

in a 1:1 orbital resonance with Jupiter. It is located in the trailering Trojan camp 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 ° behind its orbit . It is also a non- family asteroid of the Jovian background population. It orbits the Sun at a distance of 5.0–5.4 AU once every 11 years and 12 months (4,378 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 5.24 AU). Its orbit has an eccentricity of 0.04 and a high inclination of 43 ° 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 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 September 1953, or 46 years prior to its official discovery observation at Fountain Hills.

Classification as centaur

''Periboea'' was originally listed 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 ...

(MPC) as a

. However, its location close to , its low albedo and spectral slope, as well as its estimated dynamical lifetime of more than a billion years, led to the conclusion that the formerly classified centaur is indeed a Jupiter trojan.

Numbering and naming

This minor planet was numbered by the MPC on 22 December 1999 (). On 14 May 2021, the object was named by the Working Group Small Body Nomenclature (WGSBN), after

, a mortal woman and eldest daughter of Acessamenus from Greek mythology. Periboea was the mother of Pelagon who she conceived by way of the river god Axius. Her grandson was the Trojan ally Asteropaios.

Physical characteristics

''Periboea'' is an assumed C-type asteroid. It has a V–I color index of 0.88.

Rotation period

In 2007, four rotational lightcurves of ''Periboea'' have been obtained from photometric observations with a period of 10.4 and 10.422 hours (). Best-rated lightcurve, obtained 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 ...

at the

Calar Alto Observatory The Calar Alto Observatory (Centro Astronómico Hispano en Andalucía or "Spanish Astronomical Centre in Andalusia") is an astronomical observatory located in Almería province in Spain on Calar Alto, a mountain in the Sierra de Los Filabres ra ...

over seven nights from May to June 2009, gave a

of hours with a brightness amplitude of 0.17 magnitude ().

Diameter and albedo

According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, and observations by French and Spanish astronomers, ''Periboea'' measures between 51.5 and 55.34 kilometers in diameter and its surface has an albedo between 0.053 and 0.110. The ''Collaborative Asteroid Lightcurve Link'' assumes a standard albedo of a

carbonaceous 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 ...

0.057 and calculates a diameter of 61.04 kilometers based on an absolute magnitude of 9.8.

References

External links

Asteroid Lightcurve Database (LCDB)
query form

)

– Minor Planet Center
Asteroid (12929) 1999 TZ1
at the Small Bodies Data Ferret * * {{DEFAULTSORT:Periboea 012929 Discoveries by Charles W. Juels Named minor planets 19991002