3540 Protesilaos

3540 Protesilaos

Discovery
Discovered by	F. Börngen
Discovery site	Karl Schwarzschild Obs.
Discovery date	27 October 1973
Designations
MPC designation	3540 Protesilaos
Named after	Protesilaus (Greek mythology)
Alternative names	1973 UF5 · 1978 GJ2 1985 VO1
Minor planet category	Jupiter trojan
Orbital characteristics
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc	62.32 yr (22,762 days)
Aphelion	5.8931 AU
Perihelion	4.6509 AU
Semi-major axis	5.2720 AU
Eccentricity	0.1178
Orbital period	12.11 yr (4,421 days)
Mean anomaly	105.65°
Inclination	23.294°
Longitude of ascending node	26.431°
Argument of perihelion	116.55°
Jupiter MOID	0.5239 AU
Physical characteristics
Dimensions	87.66±3.46 km 70.22±1.08 km 76.84 km (calculated)
Rotation period	8.945 h 8.95±0.02 h
Geometric albedo	0.062±0.006 0.062±0.014 0.057 (assumed)
Spectral type	C
Absolute magnitude (H)	9.00 9.3 9.38±0.38 9.4

3540 Protesilaos, provisional designation 1973 UF₅, is a carbonaceous Jupiter trojan from the Greek camp, approximately 80 kilometers in diameter. It was discovered on 27 October 1973, by German astronomer Freimut Börngen at the Karl Schwarzschild Observatory in Tautenburg, Germany.

The dark C-type asteroid is orbiting in the leading Greek camp at Jupiter's L₄ Lagrangian point, 60° ahead of its orbit (see Trojans in astronomy) with an eccentricity of 0.12 and an inclination of 23° with respect to the ecliptic. It orbits the Sun at a distance of 4.6–5.9 AU once every 12 years and 1 month (4,421 days). The first precovery was taken at Palomar Observatory in 1953, extending the asteroid's observation arc by 20 years prior to its discovery.

Two rotational light-curves were obtained by astronomer Stefano Mottola at the DLR Institute for Planetary Research (1989), and by Linda French using the Cerro Tololo Inter-American Observatory in Chile (2010). The first light-curve gave a rotation period of 8.945 hours with a brightness amplitude of 0.13 in magnitude (U=2). The second light-curve showed a nearly identical period of 8.95±0.02 hours with no brightness variation given (U=2).

According to the surveys carried out by the Japanese Akari satellite, and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, the Trojan asteroid has a concurring albedo of 0.062, but measures 87.7 and 70.2 kilometers in diameter, respectively. The Collaborative Asteroid Lightcurve Link assumes a standard albedo for carbonaceous asteroids of 0.057, and calculates a diameter of 76.8 kilometers.

The minor planet is named after the hero Protesilaus from Greek mythology. In the Trojan War, he was the first Greek to set foot on the shores of Troy. He was later killed by the Trojan Aeneas, after whom one of the largest Jupiter trojans, 1172 Äneas, is named. Another Jupiter trojan, 13062 Podarkes, is named after his brother Podarkes. Naming citation was published on 14 April 1987 (M.P.C. 11751).

External links

• Asteroid Lightcurve Database (LCDB), query form (info)
• Dictionary of Minor Planet Names, Google books
• Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
• Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
• 3540 Protesilaos at the JPL Small-Body Database

• Discovery · Orbit diagram · Orbital elements · Physical parameters