Discovered by N. G. Thomas MPC designation 2895 Memnon Alternative names 1981 AE1 · 1981 CL Absolute magnitude 9.3 Discoverer Norman G. Thomas Asteroid group Jupiter trojan | Discovery date 10 January 1981 Pronunciation ˈmɛmnɒn (mem-non) Discovered 10 January 1981 Orbits Sun Discovery site Anderson Mesa Station | |
Named after Memnon
(Greek mythology) Similar Jupiter trojan, 617 Patroclus, Sun, 4581 Asclepius, 4544 Xanthus | ||
2895 Memnon (MEM-non), provisional designation 1981 AE1, is a carbonaceous Jupiter trojan from the Trojan camp, approximately 56 kilometers in diameter. It was discovered on 10 January 1981, by American astronomer Norman G. Thomas at Lowell's Anderson Mesa Station near Flagstaff, Arizona, United States.
Memnon is a C-type asteroid and resides in the Trojan camp of Jupiter's L5 Lagrangian point, which lies 60° behind the gas giant's orbit (see Trojans in astronomy). It orbits the Sun at a distance of 5.0–5.5 AU once every 11 years and 12 months (4,380 days). Its orbit has an eccentricity of 0.05 and an inclination of 27° with respect to the ecliptic. Due to a precovery taken at the Australian Siding Spring Observatory in 1977, Memnon's observation arc begins 4 years prior to its official discovery observation.
The first rotational light-curve of Memnon was obtained by Richard P. Binzel in the early 1980s. It gave a rotation period of 7.5 hours with a brightness variation of 0.24 magnitude (U=2). In November 1990, Italian ESO astronomer Stefano Mottola obtained a period of 7.502 hours with an amplitude of 0.22 magnitude (U=3-). In January 2015 and 2016, photometric observations by amateur astronomer Robert D. Stephens gave a period of 7.55 and 7.509 hours, with a brightness variation of 0.33 and 0.08, respectively (U=2/n.a.).
According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Memnon measures 56.70 kilometers in diameter, and its surface has an albedo of 0.060, while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for carbonaceous asteroids of 0.057 and calculates a diameter of 55.67 kilometers, using an absolute magnitude of 10.0.
This Trojan asteroid was named for Memnon from Greek mythology. He was the king of Ethiopia and nephew of king Priam of Troy. He supported the Trojan side in the Trojan War with 10,000 men and was killed in combat by Achilles. Naming citation was published on 20 December 1983 (M.P.C. 8405).