385571 Otrera, provisional designation , is a

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

leading

Neptune Neptune is the eighth and farthest known planet from the Sun. It is the List of Solar System objects by size, fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 t ...

's orbit in the

outer Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sol ...

. It was discovered 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 S ...

and

Chad Trujillo Chadwick A. Trujillo (born November 22, 1973) is an American astronomer, discoverer of minor planets and the co-discoverer of Eris, the most massive dwarf planet known in the Solar System. Trujillo works with computer software and has examined ...

Las Campanas Observatory Las Campanas Observatory (LCO) is an astronomy, astronomical observatory managed by the Carnegie Institution for Science (CIS). Located in Chile's Atacama Region, it sits about northeast of the city of La Serena, Chile, La Serena. The LCO's telesc ...

on 16 October 2004. It measures approximately 100 kilometers in diameter and was the second such body to be discovered after .

Orbit and classification

Neptune trojans are

resonant trans-Neptunian object In astronomy, a resonant trans-Neptunian object is a trans-Neptunian object (TNO) in mean-motion orbital resonance with Neptune. The orbital periods of the resonant objects are in a simple integer relations with the period of Neptune, e.g. 1:2, 2 ...

s in a 1:1 mean-motion

orbital resonance In celestial mechanics, orbital resonance occurs when orbiting bodies exert regular, periodic gravitational influence on each other, usually because their orbital periods are related by a ratio of small integers. Most commonly, this relation ...

with Neptune. These Trojans have a

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 longe ...

and an

orbital period The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets ...

very similar to Neptune's (30.10 AU; 164.8 years). ''Otrera'' belongs to the group, which leads 60 ° ahead Neptune's orbit. It orbits the Sun with a

of 30.027 AU at a distance of 29.3–30.7 AU once every 164 years and 6 months (60,099 days). 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-Centre (geometry), center, in geometry * Eccentricity (g ...

of 0.02 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 reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...

of 1 ° with respect to the

ecliptic The ecliptic or ecliptic plane is the orbital plane of Earth's orbit, Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making. Fr ...

Physical characteristics

The discoverers estimate that the body has a mean-diameter of 100 kilometers based on a

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 ...

of 23.3. Based on a generic magnitude-to-diameter conversion, it measures approximately 74 kilometers in diameter using an absolute magnitude of 8.8 and an assumed

albedo Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...

of 0.10.

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 ''minor ...

was the first Neptune trojan to be named in November 2015. It was named after

Otrera In Greek mythology, Otrera ( ''Otrērē'') was the founder and first Queen of the Amazons; the consort of Ares and mother of Hippolyta and Penthesilea. She is credited with being the founder of the shrine of Artemis in Ephesus. Mythology Quee ...

, the first Amazonian queen in

Greek mythology Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of ancient Greek folklore, today absorbed alongside Roman mythology into the broader designation of classical mythology. These stories conc ...

. The naming scheme is to name these objects after figures related to the

Amazons The Amazons (Ancient Greek: ', singular '; in Latin ', ') were a people in Greek mythology, portrayed in a number of ancient epic poems and legends, such as the Labours of Hercules, Labours of Heracles, the ''Argonautica'' and the ''Iliad''. ...

, which was an all-female warrior tribe that fought in the

Trojan War The Trojan War was a legendary conflict in Greek mythology that took place around the twelfth or thirteenth century BC. The war was waged by the Achaeans (Homer), Achaeans (Ancient Greece, Greeks) against the city of Troy after Paris (mytho ...

on the side of the Trojans against the Greeks.

References

External links

* * * {{DEFAULTSORT:Otrera 385571 Discoveries by Chad Trujillo Discoveries by Scott S. Sheppard Named minor planets 20041016