13963 Euphrates (), provisional designation , is a resonant Griqua asteroid from the outer region of the
asteroid belt
The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, c ...
, approximately 9 kilometers in diameter. It was discovered on 3 August 1991, by Belgian astronomer
Eric Elst
Eric Walter Elst (30 November 1936 – 2 January 2022) was a Belgian astronomer at the Royal Observatory of Belgium in Uccle and a prolific discoverer of asteroids. The Minor Planet Center ranks him among the top 10 discoverers of minor planets ...
at
ESO
The European Organisation for Astronomical Research in the Southern Hemisphere, commonly referred to as the European Southern Observatory (ESO), is an intergovernmental research organisation made up of 16 member states for ground-based ast ...
's
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 ...
site in Chile. The asteroid was named after the
Euphrates
The Euphrates () is the longest and one of the most historically important rivers of Western Asia. Together with the Tigris, it is one of the two defining rivers of Mesopotamia ( ''the land between the rivers''). Originating in Turkey, the Eup ...
River in the Middle East.
Orbit and classification
''Euphrates'' is one of very few bodies located in the 2:1
mean motion 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 relationsh ...
with the gas giant
Jupiter
Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth t ...
and belongs to the "marginally unstable"
Griqua group A Hecuba-gap asteroid is a member of a dynamical group of resonant asteroids located in the Hecuba gap at 3.27 AU – one of the largest Kirkwood gaps in the asteroid belt, which is considered the borderline separating the outer main belt as ...