, provisional designation , is a

binary Binary may refer to: Science and technology Mathematics * Binary number, a representation of numbers using only two digits (0 and 1) * Binary function, a function that takes two arguments * Binary operation, a mathematical operation that t ...

and

plutino In astronomy, the plutinos are a dynamical group of trans-Neptunian objects that orbit in 2:3 mean-motion resonance with Neptune. This means that for every two orbits a plutino makes, Neptune orbits three times. The dwarf planet Pluto is the lar ...

. It consists of two components less than 60 kilometers in diameter, orbiting at a distance of 21000 km. Mors–Somnus was discovered on 14 October 2007, 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 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 ...

with the

Subaru telescope is the telescope of the National Astronomical Observatory of Japan, located at the Mauna Kea Observatory on Hawaii. It is named after the open star cluster known in English as the Pleiades. It had the largest monolithic primary mirror in the wo ...

Mauna Kea Observatories The Mauna Kea Observatories (MKO) are a group of independent astronomical research facilities and large telescope observatories that are located at the summit of Mauna Kea on the Big Island of Hawaiʻi, United States. The facilities are located ...

in Hawaii, United States. It was later named after the twins Mors and

Somnus In Roman mythology, Somnus ("sleep") is the personification of sleep. His Greek counterpart is Hypnos. Somnus resided in the underworld. According to Virgil, Somnus was the brother of Death (Mors (mythology), Mors), and according to Ovid, Somnus ...

from Roman mythology.

Orbit and binarity

''Mors–Somnus'' is a small double

occupying the 3:2 mean motion resonance with

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

. The object is a wide optically resolved binary with the following orbital parameters: The components has almost equal size.

Physical properties

The total mass of the system is . For a realistic minimal density of 0.5 g/cm³ the

albedo Albedo (; ) is the measure of the diffuse reflection of sunlight, 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 ...

is >0.17 and the size of the components is <60 km. The ''Collaborative Asteroid Lightcurve Link'' assumes an albedo of 0.1 and calculates a diameter of 175.20 kilometers based on an

absolute magnitude Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse Logarithmic scale, logarithmic Magnitude (astronomy), astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent mag ...

of 6.9. ''Mors–Somnus'' has an ultra-red spectrum in the visible and near-infrared parts of the spectrum. The colors of two components are indistinguishable from each other. It demonstrates a double-peaked light curve with the period of about 9.28 hours and amplitude of 0.24. This indicates that either primary of secondary has an elongated shape and rotates non-synchronuosly.

Evolution

The ''Mors–Somnus'' system is likely to be an escaped cold classical Kuiper belt object.

Naming

The

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 named after the mythological twin Roman gods of death ( Mors) and sleep (

). The approved 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 2 June 2015 ().

References

External links

Asteroid Lightcurve Database (LCDB)
query form

)
Dictionary of Minor Planet Names
Google books

– Minor Planet Center * * {{DEFAULTSORT:Mors-Somnus 341520 Discoveries by Scott S. Sheppard Discoveries by Chad Trujillo Named minor planets Binary trans-Neptunian objects 20071014