283 Emma
283 Emma is a large asteroid of the asteroid belt and the namesake of the Emma family. It was discovered by Auguste Charlois on 8 February 1889, in Nice, France. The reason for its name is unknown.
A three-dimensional model of 283 Emma based on its light curve | |
| Discovery | |
|---|---|
| Discovered by | Auguste Charlois |
| Discovery date | 8 February 1889 |
| Designations | |
MPC designation | (283) Emma |
| Pronunciation | /ˈɛmə/ |
Alternative designations | A889 CA, 1980 FJ12 |
Minor planet category | Main belt (Emma) |
| Orbital characteristics | |
| Epoch 31 July 2016 (JD 2457600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 122.26 yr (44655 d) |
| Aphelion | 3.49701 AU (523.145 Gm) |
| Perihelion | 2.59675 AU (388.468 Gm) |
Semi-major axis | 3.04688 AU (455.807 Gm) |
| Eccentricity | 0.14773 |
Orbital period (sidereal) | 5.32 yr (1942.6 d) |
Average orbital speed | 17.07 km/s |
Mean anomaly | 127.107° |
Mean motion | 0° 11m 7.148s / day |
| Inclination | 7.99162° |
Longitude of ascending node | 304.369° |
| 53.7020° | |
| Known satellites | 1 (9±5 km) |
| Physical characteristics | |
| Dimensions | 148.06±4.6 km (IRAS) 160±10 km (AO) |
| Mass | 1.38×1018 kg |
Mean density | 0.81±0.08 g/cm3 |
Synodic rotation period | 6.896 h (0.2873 d) |
| 0.0262±0.002 (Dark) | |
| 8.72 | |
Measurements made with the IRAS observatory give a diameter of 145.70 ± 5.89 km and a geometric albedo of 0.03 ± 0.01. By comparison, the MIPS photometer on the Spitzer Space Telescope gives a diameter of 145.44 ± 7.72 km and a geometric albedo of 0.03 ± 0.01. When the asteroid was observed occulting a star, the results showed a diameter of 148.00 ± 16.26 km.
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