, '' prov. designation'': , is a minor planet and the first

Neptune trojan Neptune trojans are bodies that orbit the Sun near one of the stable Lagrangian points of Neptune, similar to the Trojan (astronomy), trojans of other planets. They therefore have approximately the same orbital period as Neptune and follow rough ...

discovered, by American astronomer Marc Buie of the

Deep Ecliptic Survey The Deep Ecliptic Survey (DES) is a project to find Kuiper belt objects (KBOs), using the facilities of the National Optical Astronomy Observatory (NOAO). The principal investigator is Robert L. Millis. Since 1998 through the end of 2003, the sur ...

Cerro Tololo Observatory The Cerro Tololo Inter-American Observatory (CTIO) is an astronomical observatory located on Cerro Tololo in the Coquimbo Region of northern Chile, with additional facilities located on Cerro Pachón about to the southeast. It is approximately ...

in Chile on 21 August 2001. It orbits ahead of Neptune at its

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 ...

and measures approximately in diameter. Other Neptune trojans have been discovered since. A study by American astronomers

Scott Sheppard Scott Sander Sheppard (born 1977) is an American astronomer and a discoverer of numerous moons, comets and minor planets in the outer Solar System. He is an astronomer in the Department of Terrestrial Magnetism at the Carnegie Institution for Scie ...

and Chad Trujillo from the Carnegie Institution suggests that Neptune could possibly have twenty times more trojans than Jupiter.

Orbit

orbits the Sun with a semi-major axis of 30.115 AU at a distance of 29.3–31.0 AU once every 165 years and 3 months (60,363 days). Its orbit has an eccentricity of 0.03 and an inclination of 1 ° with respect to the ecliptic.

Dynamical stability

Early studies of the dynamical stability of , which used a small number of test particles spread over the uncertainties of just a few orbital parameters that were derived from a limited observation arc, suggested that is on a remarkably stable orbit, because most test particles remained on trojan orbits for 5 Gyr. Thereafter, the stability of Neptune trojans was simply assumed. A more recent study, which used a very large number of test particles spread over the 3 σ uncertainties in all six orbital parameters derived from a longer observational arc, has indicated that is far less dynamically stable than previously thought. The test particles were lost exponentially with a

half life Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable at ...

of 553 Myr. Further observations can determine whether 's orbit is actually within the dynamically stable or within the unstable part. The stability is strongly dependent on

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 ...

, with a≥30.30 AU being far less stable, but only very weakly dependent on the other orbital parameters. This is because those with larger semi-major axes have larger

libration In lunar astronomy, libration is the wagging or wavering of the Moon perceived by Earth-bound observers and caused by changes in their perspective. It permits an observer to see slightly different hemispheres of the surface at different tim ...

amplitudes, with amplitudes ~70° and above being destabilized by secondary resonances between the trojan motion and the dynamics of at least

Saturn Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine and a half times that of Earth. It has only one-eighth the average density of Earth; h ...

, Uranus, and Neptune.

Secular resonance A secular resonance is a type of orbital resonance between two bodies with synchronized precessional frequencies. In celestial mechanics, secular refers to the long-term motion of a system, and resonance is periods or frequencies being a simple nu ...

s were found not to contribute to the dynamical stability of .

Numbering and naming

This minor planet was numbered and its discoverer determined 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 28 March 2022 (). If named, it will follow the naming scheme already established with

385571 Otrera 385571 Otrera, provisional designation , is a Neptune trojan leading Neptune's orbit in the outer Solar System. It was discovered by American astronomers Scott Sheppard and Chad Trujillo at Las Campanas Observatory on 16 October 2004. It measures ...

, which is to name these objects after figures related to the

Amazons In Greek mythology, the Amazons (Ancient Greek: Ἀμαζόνες ''Amazónes'', singular Ἀμαζών ''Amazōn'', via Latin ''Amāzon, -ŏnis'') are portrayed in a number of ancient epic poems and legends, such as the Labours of Hercules, ...

, an all-female warrior tribe that fought in the Trojan War on the side of the Trojans against the Greek.

Physical characteristics

The discoverers estimate that the body has a mean diameter of 132 kilometers with a low albedo of 0.058 at an absolute magnitude of 8.12. It has a visual magnitude of 22.5.

References

External links

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