(5261) Eureka

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Asteroid
(5261) Eureka
Properties of the orbit ( animation )
Epoch:  March 23, 2018 ( JD 2,458,200.5)
Orbit type Mars Trojan (L 5 )
family  
Major semi-axis 1.524  AU
eccentricity 0.065
Perihelion - aphelion 1.425 AU - 1.622 AU
Inclination of the orbit plane 20.3 °
Length of the ascending node 245 °
Argument of the periapsis 95.5 °
Sidereal period 686.87 d
Mean orbital velocity 24.105 km / s
Physical Properties
Medium diameter 1.878 ± 0.231 km
Albedo 0.182 ± 0.054
Rotation period 2.6902 h
Absolute brightness 16.1 mag
Spectral class SMASSII: Sr
history
Explorer David H. Levy , Henry E. Holt
Date of discovery June 20, 1990
Another name 1990 MB
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . The affiliation to an asteroid family is automatically determined from the AstDyS-2 database . Please also note the note on asteroid items.

(5261) Eureka was the first asteroid found in the group of Mars Trojans . As Trojans are called asteroids that planets follow their path by 60 ° or run ahead. It was discovered on June 20, 1990 by David H. Levy and Henry E. Holt .

The name is derived from " Eureka " (Greek: "I found it"), a saying that Archimedes is said to have made when he recognized the principle of buoyancy.

After its discovery, Eureka could be identified in photos going back to 1979. In January 2018, 906 observations were made over a period of 38 years from 16 oppositions.

The almost 1.9 km large Eureka follows the planet at the Lagrange point L 5 of Mars' orbit around the sun. The perihelion distance is 1.425  AU , the aphelion distance 1.622 AU. The orbit has an eccentricity of 0.065 and is strongly inclined to the ecliptic at 20.28 ° .

moon

On November 28, 2011, a small Eureka moon was discovered. Its provisional designation is S / 2011 (5261) 1 . It has a diameter of about 460 m and circles Eureka at a distance of 2.1 km in 0.7054 ± 0.0004 days. The discovery was announced in September 2014.

See also

Individual evidence

  1. ↑ v ≈ π * a / period (1 + sqrt (1-e²))
  2. ^ A b C. R. Nugent, A. Mainzer, J. Masiero, J. Bauer, RM Cutri, T. Grav, E. Kramer, S. Sonnett, R. Stevenson, EL Wright: NEOWISE Reactivation Mission Year One: Preliminary Asteroid Diameters and Albedos . In: Astrophysical Journal . 814, No. 2, November 24, 2015, p. 117. arxiv : 1509.02522 . bibcode : 2015ApJ ... 814..117N . doi : 10.1088 / 0004-637X / 814/2/117 .
  3. ↑ (5261) Eureka in the Small-Body Database of the Jet Propulsion Laboratory (English). Retrieved February 10, 2018.
  4. ↑ (5261) Eureka at the IAU Minor Planet Center (English). Accessed February 10, 2018.
  5. ^ Robert Johnston: (5261) Eureka. Johnston's Archives, November 16, 2014, accessed February 10, 2018 .