5692 Shirao, provisional designation , is a stony Eunomia
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 ...
from the middle region 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 ...
, approximately 9 kilometers in diameter. It was discovered on 23 March 1992, by Japanese amateur astronomers
Kin Endate and
Kazuro Watanabe at
Kitami Observatory
Kitami Observatory is an astronomical observatory in the Kitami-Abashiri Region Cultural Centre in eastern Hokkaidō, Japan. Its observatory code is 400. It is 0.72344 Earth radii from the rotation axis and +0.68811 Earth radii from the equatorial ...
, Hokkaidō, Japan.
The asteroid was later named for Japanese geologist and
astrophotographer Motomaro Shirao.
Orbit and classification
''Shirao'' is a member of the
Eunomia family The Eunomia or Eunomian family () is a large asteroid family of S-type asteroids named after the asteroid 15 Eunomia. It is the most prominent family in the intermediate asteroid belt and the 6th-largest family with nearly six thousand known member ...
, a large group of
stony asteroids and the most prominent family in the intermediate main-belt. It orbits the Sun in the
central main-belt at a distance of 2.2–3.1
AU once every 4 years and 4 months (1,580 days). Its orbit has an
eccentricity
Eccentricity or eccentric may refer to:
* Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal"
Mathematics, science and technology Mathematics
* Off-Centre (geometry), center, in geometry
* Eccentricity (g ...
of 0.18 and an
inclination
Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object.
For a satellite orbiting the Eart ...
of 12
° with respect to the
ecliptic
The ecliptic or ecliptic plane is the orbital plane of Earth's orbit, Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making.
Fr ...
.
In 1949, it was first identified as at
Goethe Link Observatory
The Goethe Link Observatory, observatory code 760, is an astronomical observatory near Brooklyn, Indiana, United States. It is owned by Indiana University and operated by the Indiana Astronomical Society https://iasindy.org/about.html, which eff ...
. The body's
observation arc
In observational astronomy, the observation arc (or arc length) of a Solar System body is the time period between its earliest and latest observations, used for tracing the body's path. It is usually given in days or years. The term is mostly use ...
begins in 1955, with a
precovery
In astronomy, precovery (short for pre-discovery recovery) is the process of finding the image of a celestial object in images or photographic plates predating its discovery, typically for the purpose of calculating a more accurate orbit. This ha ...
at
Palomar Observatory
The Palomar Observatory is an astronomical research observatory in the Palomar Mountains of San Diego County, California, United States. It is owned and operated by the California Institute of Technology (Caltech). Research time at the observat ...
, 37 years prior to its official discovery observation at Kitami.
Physical characteristics
Rotation period
In June 2014, a rotational
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 ...
of ''Shirao'' was obtained from photometric observations made by American astronomer
Brian Warner at his Palmer Divide Observatory () in Colorado. It gave a well-defined
rotation period
In astronomy, the rotation period or spin period of a celestial object (e.g., star, planet, moon, asteroid) has two definitions. The first one corresponds to the '' sidereal rotation period'' (or ''sidereal day''), i.e., the time that the objec ...
of hours with a brightness variation of 0.16
magnitude
Magnitude may refer to:
Mathematics
*Euclidean vector, a quantity defined by both its magnitude and its direction
*Magnitude (mathematics), the relative size of an object
*Norm (mathematics), a term for the size or length of a vector
*Order of ...
().
Previous lightcurves were obtained by French astronomer
René Roy ( hours, Δ 0.13 mag, ) in June 2001,
by American astronomer
Donald P. Pray ( hours, Δ 0.12 mag, ) in March 2005,
and by astronomers Dominique Suys, Hugo Riemis and Jan Vantomme ( hours, Δ 0.15 mag, ) in September 2006.
Diameter and albedo
According to the surveys carried out by NASA's
Wide-field Infrared Survey Explorer
Wide-field Infrared Survey Explorer (WISE, List of observatory codes, observatory code C51, Explorer 92 and MIDEX-6) was a NASA infrared astronomy Space observatory, space telescope in the Explorers Program launched in December 2009.. . WISE L ...
and its subsequent
NEOWISE
Wide-field Infrared Survey Explorer (WISE, observatory code C51, Explorer 92 and MIDEX-6) was a NASA infrared astronomy space telescope in the Explorers Program launched in December 2009.. . WISE discovered thousands of minor planets and nu ...
mission, ''Shirao'' measures between 9.5 and 9.8 kilometers in diameter and its surface has an
albedo
Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...
of 0.22,
while the ''Collaborative Asteroid Lightcurve Link'' assumes a standard albedo of 0.21 – derived from
15 Eunomia
15 Eunomia is a very large asteroid in the middle asteroid belt. It is the largest of the stony ( S-type) asteroids, with 3 Juno as a close second. It is quite a massive asteroid, in 6th to 8th place (to within measurement uncertainties). It is ...
, the largest member and namesake of this asteroid family – and calculates a diameter of 9.2 kilometers.
Naming
This
minor planet
According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor ...
was named after Motomaro Shirao (born 1953), a Japanese
geologist
A geologist is a scientist who studies the structure, composition, and History of Earth, history of Earth. Geologists incorporate techniques from physics, chemistry, biology, mathematics, and geography to perform research in the Field research, ...
and
astrophotographer, who is known for his photographs of volcanoes and lunar
geological features
Geology (). is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth s ...
.
The official naming citation 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.
Funct ...
on 4 April 1996 ().
Notes
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:Shirao
005692
Discoveries by Kin Endate
Discoveries by Kazuro Watanabe
Named minor planets
19920323