(588) Achilles
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Asteroid (588) Achilles |
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| Properties of the orbit ( animation ) | |
| Orbit type | Jupiter Trojan (L 4 ) |
| Major semi-axis | 5.195 AU |
| eccentricity | 0.148 |
| Perihelion - aphelion | 4.426 AU - 5.964 AU |
| Inclination of the orbit plane | 10.3 ° |
| Length of the ascending node | 316.6 ° |
| Argument of the periapsis | 132.5 ° |
| Time of passage of the perihelion | June 10, 2011 |
| Sidereal period | 11 a 307 d |
| Mean orbital velocity | 13.0 km / s |
| Physical Properties | |
| Medium diameter | 135.47 km |
| Albedo | 0.03 |
| Rotation period | 7 h 18 min |
| Absolute brightness | 8.7 likes |
| history | |
| Explorer | Max Wolf |
| Date of discovery | February 22, 1906 |
| Another name | 1906 TG |
| 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. | |
(588) Achilles is an asteroid from the group of the Jupiter Trojans , so it moves on the orbit of Jupiter around the sun.
Achilles was discovered by Max Wolf on February 22, 1906 as the first Trojan horse and is named after the Greek hero Achilles from the Iliad . The name of the asteroid was originally suggested by Johann Palisa , a friend and colleague of Max Wolf.
The asteroid is ahead of Jupiter on its orbit by 60 ° (it is at the Lagrange point L 4 ). The Trojans running ahead are also known as Greeks and are therefore named after ancient Greek heroes. The orbit of Achilles runs between 4.4 ( perihelion ) and 6.0 ( aphelion ) astronomical units and is inclined 10 ° to the ecliptic . The orbital eccentricity is 0.15.
During the opposition, Achilles reaches an apparent magnitude of 16.6 mag . It is therefore an extremely faint object in the night sky.
In addition to its small size, Achilles' low albedo (reflectivity) is also responsible for its low brightness. It only reflects 3.3% of the incident light, so it is blacker than asphalt, for example . According to measurements at NASA's Infrared Telescope Facility (IRTF), its surface is probably made up of 20 to 40% pyroxene (various silicates ). Iron is likely to be responsible for the observed red coloration of the reflected portion . More than 10% tholine components , i.e. methane and ethane components transformed by ultraviolet light , could be excluded by spectral analyzes for the surface . The surface is also poor in chlorites (maximum 1%).
See also
literature
- Icarus : Volume 164, Issue 1, pp. 104-121: 7/2003: Constraints on the surface composition of Trojan asteroids from near-infrared (0.8-4.0 μm) spectroscopy: Emery, JP; Brown, RH: Article available online on the Icarus server (in English): doi : 10.1016 / S0019-1035 (03) 00143-X
- Icarus : Volume 170, Issue 1, pp. 131-152: 7/2004: The surface composition of Trojan asteroids: constraints set by scattering theory: Emery, JP; Brown, RH: Article available online on the Icarus server (in English): doi : 10.1016 / j.icarus.2004.02.004