| Minorplanet: | yes |
| Background: |
|
| 283 Emma | |
| Discovered: | 8 February 1889 |
| Mpc Name: | (283) Emma |
| Alt Names: | A889 CA, |
| Mp Category: | Main belt (Emma) |
| Epoch: | 31 July 2016 (JD 2457600.5) |
| Semimajor: | 3.04688AU |
| Perihelion: | 2.59675AU |
| Aphelion: | 3.49701abbr=onNaNabbr=on |
| Eccentricity: | 0.14773 |
| Period: | 5.32 yr (1942.6 d) |
| Inclination: | 7.99162° |
| Asc Node: | 304.369° |
| Arg Peri: | 53.7020° |
| Avg Speed: | 17.07 km/s |
| Satellites: | 1 (9±5 km) |
| Dimensions: | 160±10 km (AO) |
| Mass: | 1.38 kg[1] |
| Density: | 0.81±0.08 g/cm3 |
| Rotation: | 6.896abbr=onNaNabbr=on |
| Abs Magnitude: | 8.72 |
| Albedo: | (Dark) |
| Mean Motion: | / day |
| Observation Arc: | 122.26 yr (44655 d) |
| Uncertainty: | 0 |
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.[2]
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.
A companion for 283 Emma was detected on 14 July 2003 by W. J. Merline et al. using the Keck II telescope and is designated S/2003 (283) 1. The discovery was reported in the International Astronomical Union Circular (IAUC) 8165.[3] The satellite orbits at a semi-major axis of about 581 km with an eccentricity of 0.12. Emma has a Hill sphere with a radius of about 28,000 km.