13963 Euphrates
Main-belt asteroid
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13963 Euphrates (/juËËfreɪtiËz/), provisional designation 1991 PT4, is a resonant Griqua asteroid from the outer region of the asteroid belt, approximately 9 kilometers in diameter. It was discovered on 3 August 1991, by Belgian astronomer Eric Elst at ESO's La Silla Observatory site in Chile.[5] The asteroid was named after the Euphrates River in the Middle East.[2]
| Discovery[1] | |
|---|---|
| Discovered by | E. W. Elst |
| Discovery site | La Silla Obs. |
| Discovery date | 3 August 1991 |
| Designations | |
| (13963) Euphrates | |
| Pronunciation | /juËËfreɪtiËz/ |
Named after | Euphrates[2] (river in Mesopotamia) |
| 1991 PT4 · 1997 TO10 | |
| main-belt · (outer)[1] Griqua[3] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 45.98 yr (16,793 days) |
| Aphelion | 4.1853 AU |
| Perihelion | 2.4762 AU |
| 3.3307 AU | |
| Eccentricity | 0.2566 |
| 6.08 yr (2,220 days) | |
| 84.506° | |
| 0° 9m 43.56s / day | |
| Inclination | 0.9360° |
| 227.18° | |
| 129.72° | |
| TJupiter | 3.1090 |
| Physical characteristics | |
| Dimensions | 9±1 km (est. at 0.06)[4] |
| 13.9[1] | |
Orbit and classification
Euphrates is one of very few bodies located in the 2:1 mean motion resonance with the gas giant Jupiter and belongs to the "marginally unstable" Griqua group.[3]
It orbits the Sun in the outer main-belt at a distance of 2.5â4.2 AU once every 6 years and 1 month (2,220 days). Its orbit has an eccentricity of 0.26 and an inclination of 1° with respect to the ecliptic.[1] A first precovery was taken at Palomar Observatory in 1971, extending the asteroid's observation arc by 20 years prior to its official discovery observation.[5]
Physical characteristics
Based on an absolute magnitude of 13.9, it measures between 4 and 10 kilometers in diameter, assuming an albedo in the range of 0.05 to 0.25. Since asteroids in the outer main-belt are mostly of a carbonaceous rather than of a silicaceous composition, with low albedos, typically around 0.06, its diameter is likely to be between 8 and 10 kilometers.[4]
As of 2017, Euphrates' effective size, its composition and albedo, as well as its rotation period and shape remain unknown.[1][6]
Naming
This minor planet was named after the Euphrates river, that flows through northern Syria and Iraq.[2]
It is one of the most historically important rivers of Western Asia. The TigrisâEuphrates river system, a major river system, is formed when the two rivers combine at Al Qurnah. The minor planet 13096 Tigris is named after the other river of this system.[2] The approved naming citation was published by the Minor Planet Center on 6 August 2003 (M.P.C. 49280).[7]
