.png) A three-dimensional model of 283 Emma based on its light curve | |
| Discovery | |
|---|---|
| Discovered by | Auguste Charlois |
| Discovery date | 8 February 1889 |
| Designations | |
| (283) Emma | |
| Pronunciation | /ˈɛmə/[1] |
| A889 CA,1980 FJ12 | |
| Main belt (Emma) | |
| Orbital characteristics[2] | |
| 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) |
| 3.04688 AU (455.807 Gm) | |
| Eccentricity | 0.14773 |
| 5.32yr (1942.6d) | |
Averageorbital speed | 17.07 km/s |
| 127.107° | |
| 0° 11m 7.148s / day | |
| Inclination | 7.99162° |
| 304.369° | |
| 53.7020° | |
| Knownsatellites | 1 (9±5 km)[3] |
| Physical characteristics | |
| Dimensions | 148.06±4.6 km(IRAS)[2] 160±10 km (AO)[3] |
| Mass | 1.38×1018 kg[4] |
Meandensity | 0.81±0.08 g/cm3[4] |
| 6.896 h (0.2873 d)[2] | |
| 0.0262±0.002[2] (Dark) | |
| 8.72[2] | |
283 Emma is a largeasteroid of theasteroid belt and the namesake of theEmma family. It was discovered byAuguste Charlois on 8 February 1889, inNice, France. The reason for its name is unknown.[5]
Measurements made with theIRAS observatory give a diameter of145.70±5.89 km and ageometric albedo of0.03±0.01. By comparison, the MIPSphotometer on theSpitzer Space Telescope gives a diameter of145.44±7.72 km and a geometric albedo of0.03±0.01. When the asteroid was observedocculting a star, the results showed a diameter of148.00±16.26 km.[6]
A companion for 283 Emma was detected on 14 July 2003 by W. J. Merline et al. using theKeck II telescope and is designatedS/2003 (283) 1. The discovery was reported in theInternational Astronomical Union Circular (IAUC) 8165.[7] The satellite orbits at asemi-major axis of about 581 km with an eccentricity of 0.12.[3] Emma has aHill sphere with a radius of about 28,000 km.[3]
