86 Semele

86 Semele

Discovery
Discovered by	Friedrich Tietjen
Discovery date	January 4, 1866
Designations
Named after	Semele
Minor planet category	Main belt
Orbital characteristics[1]
Epoch December 31, 2006 (JD 2454100.5)
Aphelion	562.652 Gm (3.761 AU)
Perihelion	369.116 Gm (2.467 AU)
Semi-major axis	465.884 Gm (3.114 AU)
Eccentricity	0.208
Orbital period	2,007.366 d (5.50 a)
Average orbital speed	16.69 km/s
Mean anomaly	264.875°
Inclination	4.822°
Longitude of ascending node	86.452°
Argument of perihelion	307.886°
Physical characteristics
Dimensions	120.6 km
Mass	1.8×10^18 kg
Surface gravity	0.0337 m/s²
Escape velocity	0.0638 km/s
Albedo	0.047 [2]
Temperature	~158 K
Spectral type	C
Absolute magnitude (H)	8.54

86 Semele (/ˈsɛmᵻliː/ SEM-i-lee) is a large and very dark main-belt asteroid. It is probably composed of carbonates. Semele was discovered by German astronomer Friedrich Tietjen on January 4, 1866.^[3] It was his first and only asteroid discovery. It is named after Semele, the mother of Dionysus in Greek mythology.

The orbit of 86 Semele places it in a 13:6 mean motion resonance with the planet Jupiter. The computed Lyapunov time for this asteroid is only 6,000 years, indicating that it occupies a chaotic orbit that will change randomly over time because of gravitational perturbations of the planets. This Lyapunov time is the second lowest among the first 100 named minor planets.^[4]

References

1. Yeomans, Donald K., "86 Semele", JPL Small-Body Database Browser (NASA Jet Propulsion Laboratory), retrieved 2013-04-07.
2. Asteroid Data Sets
3. "Numbered Minor Planets 1–5000", Discovery Circumstances (IAU Minor Planet center), retrieved 2013-04-07.
4. Šidlichovský, M. (1999), Svoren, J.; Pittich, E. M.; Rickman, H., eds., "Resonances and chaos in the asteroid belt", Evolution and source regions of asteroids and comets : proceedings of the 173rd colloquium of the International Astronomical Union, held in Tatranska Lomnica, Slovak Republic, August 24–28, 1998, pp. 297–308, Bibcode:1999esra.conf..297S.

External links

• 86 Semele at the JPL Small-Body Database

• Discovery · Orbit diagram · Orbital elements · Physical parameters