283 Emma is a large

asteroid An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...

of the

asteroid belt The asteroid belt is a torus-shaped region in the Solar System, centered on the Sun and roughly spanning the space between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies called asteroids ...

and the namesake of the Emma family. It was discovered by

Auguste Charlois Auguste Honoré Charlois (; November 26, 1864 – March 26, 1910) was a French astronomer who discovered 99 asteroids while working at the Nice Observatory in southeastern France. Asteroid discovery His first discovery was the asteroid 267 Tirz ...

on 8 February 1889, in

Nice Nice ( ; ) is a city in and the prefecture of the Alpes-Maritimes department in France. The Nice agglomeration extends far beyond the administrative city limits, with a population of nearly one million IRAS The Infrared Astronomical Satellite (Dutch language, Dutch: ''Infrarood Astronomische Satelliet'') (IRAS) was the first space telescope to perform a astronomical survey, survey of the entire night sky at infrared wavelengths. Launched on 25 Janu ...

observatory give a diameter of and a

geometric albedo In astronomy, the geometric albedo of a celestial body is the ratio of its actual brightness as seen from the light source (i.e. at zero phase angle (astronomy), phase angle) to that of an ''idealized'' flat, fully reflecting, diffuse reflection, d ...

of . By comparison, the MIPS

photometer A photometer is an instrument that measures the strength of electromagnetic radiation in the range from ultraviolet to infrared and including the visible spectrum. Most photometers convert light into an electric current using a photoresistor, ...

on the

Spitzer Space Telescope The Spitzer Space Telescope, formerly the Space Infrared Telescope Facility (SIRTF), was an infrared space telescope launched in 2003, that was deactivated when operations ended on 30 January 2020. Spitzer was the third space telescope dedicate ...

gives a diameter of and a geometric albedo of . When the asteroid was observed

occulting An occultation is an event that occurs when one object is hidden from the observer by another object that passes between them. The term is often used in astronomy, but can also refer to any situation in which an object in the foreground blocks f ...

a star, the results showed a diameter of .

Satellite

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 The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

Circular (IAUC) 8165. The satellite orbits at a

semi-major axis In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the longe ...

of about 581 km with an eccentricity of 0.12. Emma has a

Hill sphere The Hill sphere is a common model for the calculation of a Sphere of influence (astrodynamics), gravitational sphere of influence. It is the most commonly used model to calculate the spatial extent of gravitational influence of an astronomical ...

with a radius of about 28,000 km.

References

External links

Asteroids with Satellites
Robert Johnston, johnstonsarchive.net
Orbits of Binary Asteroids with Adaptive Optics
( VLT images) * * {{DEFAULTSORT:Emma 000283 Discoveries by Auguste Charlois Named minor planets 000283 000283 18890208