1922 Zulu, provisional designation , is a carbonaceous
asteroid
An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere.
...
in a strongly unstable resonance with Jupiter, located in the outermost regions of the
asteroid belt, and approximately 20 kilometers in diameter. It was discovered on 25 April 1949, by South African astronomer
Ernest Johnson at
Union Observatory
Union Observatory also known as Johannesburg Observatory ( 078) is a defunct astronomical observatory in Johannesburg, South Africa that was operated between 1903 and 1971. It is located on Observatory Ridge, the city's highest point at 1,808 met ...
in Johannesburg, and named for the South African
Zulu people.
Orbit and classification
''Zulu'' is one of few strongly unstable asteroids located near the 2:1
orbital resonance with the gas giant
Jupiter, that corresponds to one of the prominent
Kirkwood gaps in the asteroid belt.
It orbits the Sun at a distance of 1.7–4.8
AU once every 5 years and 10 months (2,126 days). Its orbit has an
eccentricity of 0.48 and an
inclination of 35
° with respect to the
ecliptic.
The body's
observation arc begins with its official discovery observation at Johannesburg, as no
precoveries were taken and no prior identifications were made.
''Zulu'' was lost shortly after its 1949-discovery ''(see
Lost asteroid)'', and only rediscovered in 1974 by Richard Eugene McCrosky, Cheng-yuan Shao and JH Bulger based on a predicted position by C. M. Bardwell of the
Cincinnati Observatory.
It is quite highly inclined for asteroids in the asteroid belt, with an inclination of 35.4 degrees. This may be related to its 2:1 resonance with Jupiter.
Physical characteristics
In May 2002, a rotational
lightcurve of ''Zulu'' was obtained from photometric observations by American astronomer
Robert Stephens
Sir Robert Graham Stephens (14 July 193112 November 1995) was a leading English actor in the early years of Britain's Royal National Theatre. He was one of the most respected actors of his generation and was at one time regarded as the natur ...
at the Santana Observatory in California. Lightcurve analysis gave a well-defined
rotation period
The rotation period of a celestial object (e.g., star, gas giant, planet, moon, asteroid) may refer to its sidereal rotation period, i.e. the time that the object takes to complete a single revolution around its axis of rotation relative to the ...
of 18.64 hours with a brightness variation of 0.11
magnitude ().
One month later, French amateur astronomers
René Roy and Laurent Brunetto obtained another lightcurve with a concurring period of 18.65 hours and an amplitude of 0.09 magnitude ().
According to the survey carried out by NASA's
Wide-field Infrared Survey Explorer with its subsequent
NEOWISE mission, ''Zulu'' measures 12.41 and 20.561 kilometers in diameter and its surface has an
albedo of 0.055 and 0.16.
The ''Collaborative Asteroid Lightcurve Link'' assumes a standard albedo for a carbonaceous
C-type asteroid of 0.057 and calculates a diameter of 19.30 kilometers with an
absolute magnitude of 12.3.
Naming
This
minor planet was named after the South African
Zulu people, in recognition of the tribesmen who devotedly worked at the Johannesburg Union Observatory. The name also closely relates to
1362 Griqua
1362 Griqua, provisional designation is a dark, Jupiter-resonant background asteroid on an eccentric, cometary-like orbit and the namesake of the Griqua group, located in the Hecuba gap in the outermost region of the asteroid belt. The carbonac ...
and
1921 Pala
1921 Pala, provisional designation is a background asteroid in an unstable orbit located in the outer region of asteroid belt, approximately 8.2 kilometers in diameter. It is one of very few bodies located in the 2 : 1 orbital resonance, mean mo ...
, which also received tribal names and librate in the 2:1 ratio of Jupiter's mean motion as well.
The official was published by the
Minor Planet Center
The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory.
Function
...
on 20 February 1976 ().
See also
*
Griqua group
References
External links
Asteroid Lightcurve Database (LCDB) query form
)
Dictionary of Minor Planet Names Google books
– Observatoire de Genève, Raoul Behrend
– Minor Planet Center
*
*
{{DEFAULTSORT:Zulu
001922
Discoveries by Ernest Leonard Johnson
Named minor planets
19490425
Recovered astronomical objects