Discovery | |
---|---|
Discovered by | Friedrich Tietjen |
Discovery date | January 4, 1866 |
Designations | |
(86) Semele | |
Pronunciation | /ˈsɛmɪlə/ [1] |
Named after | Semele |
Main belt | |
Adjectives | Semelean /sɛmɪˈleɪən/ [2] |
Orbital characteristics [3] | |
Epoch December 31, 2006 ( JD 2454100.5) | |
Aphelion | 562.652 Gm (3.761 AU) |
Perihelion | 369.116 Gm (2.467 AU) |
465.884 Gm (3.114 AU) | |
Eccentricity | 0.208 |
2,007.366 d (5.50 a) | |
Average
orbital speed | 16.69 km/s |
264.875° | |
Inclination | 4.822° |
86.452° | |
307.886° | |
Physical characteristics | |
Dimensions | 120.6 km |
Mass | 1.8×1018 kg |
Equatorial
surface gravity | 0.0337 m/s² |
Equatorial
escape velocity | 0.0638 km/s |
16.641±0.001 h [4] | |
0.047 [5] | |
C | |
8.54 | |
Semele ( minor planet designation: 86 Semele) is a large and very dark main-belt asteroid with an orbital period of 5.5 years. It is rotating with a period of 16.6 hours, and varies in magnitude by 0.13 during each cycle. [4] This object is classified as a C-type asteroid and is probably composed of carbonates.
Semele was discovered by German astronomer Friedrich Tietjen on January 4, 1866. [6] 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. [7]