89 Julia is a large
main-belt 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 ...
that was discovered by French astronomer
Édouard Stephan
Édouard Jean-Marie Stephan (31 August 1837 – 31 December 1923) was a French astronomer. His surname is sometimes spelled Stéphan in some literature, but this is apparently erroneous.
He was born in Sainte Pezenne (today one of the districts o ...
on 6 August 1866. This was first of his two asteroid discoveries; the other was
91 Aegina. 89 Julia is believed to be named after Saint
Julia of Corsica. A
stellar occultation
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 ...
by Julia was observed on 20 December 1985.
The spectrum of 89 Julia shows the signature of
silicate
A silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is also used ...
rich minerals with possible indications of an abundant calcic
clinopyroxene component. It is classified as an
S-type asteroid. The asteroid has an estimated diameter of .
Photometry
Photometry can refer to:
* Photometry (optics), the science of measurement of visible light in terms of its perceived brightness to human vision
* Photometry (astronomy), the measurement of the flux or intensity of an astronomical object's electr ...
from the Oakley Observatory during 2006 produced a
lightcurve
In astronomy, a light curve is a graph (discrete mathematics), graph of the Radiance, light intensity of a celestial object or region as a function of time, typically with the magnitude (astronomy), magnitude of light received on the ''y''-axis ...
that indicated a
sidereal rotation period
Sidereal time ("sidereal" pronounced ) is a system of timekeeping used especially by astronomers. Using sidereal time and the celestial coordinate system, it is easy to locate the positions of celestial objects in the night sky. Sidereal ti ...
of with an
amplitude
The amplitude of a periodic variable is a measure of its change in a single period (such as time or spatial period). The amplitude of a non-periodic signal is its magnitude compared with a reference value. There are various definitions of am ...
of in magnitude.
[
]
Nonza crater and Julian family
89 Julia is the parent body of the eponymous Julia family of asteroids. Observations of 89 Julia by the VLT's SPHERE instrument identified a 'highly probable' crater 70–80 km in diameter and deep in the southern hemisphere as the only visible possible source of the family. The crater was named Nonza by the discoverers, referring to the commune on the island of Corsica where Saint Julia was born.
Notes
References
External links
*
*
{{DEFAULTSORT:Julia
000089
Discoveries by Édouard Stephan
Named minor planets
000089
000089
18660806