Cybele,
minor planet designation
A formal minor-planet designation is, in its final form, a number–name combination given to a minor planet (asteroid, centaur, trans-Neptunian object and dwarf planet but not comet). Such designation always features a leading number (catalog or ...
65 Cybele, is one of the
largest asteroids
The following is a collection of lists of asteroids of the Solar System that are exceptional in some way, such as their size or orbit. For the purposes of this article, "asteroid" refers to minor planets out to the orbit of Neptune, and includ ...
in the
Solar System. It is located in the outer
asteroid belt. It is thought to be a remnant primordial body.
It gives its name to the
Cybele group of asteroids that orbit outward from the Sun from the 2:1
orbital resonance with
Jupiter. The
X-type asteroid has a relatively short
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 6.0814 hours. It was discovered by
Wilhelm Tempel
Ernst Wilhelm Leberecht Tempel (4 December 1821 – 16 March 1889), normally known as Wilhelm Tempel, was a German astronomer who worked in Marseille until the outbreak of the Franco-Prussian War in 1870, then later moved to Italy.
Tempel was b ...
in 1861, and named after
Cybele, the earth goddess.
Discovery and naming
''Cybele'' was discovered on 8 March 1861, by German astronomer
Wilhelm Tempel
Ernst Wilhelm Leberecht Tempel (4 December 1821 – 16 March 1889), normally known as Wilhelm Tempel, was a German astronomer who worked in Marseille until the outbreak of the Franco-Prussian War in 1870, then later moved to Italy.
Tempel was b ...
from the
Marseilles Observatory
Marseille Observatory (french: Observatoire de Marseille) is an astronomical observatory located in Marseille, France, with a history that goes back to the early 18th century. In its 1877 incarnation, it was the discovery site of a group of gala ...
in southeastern France.
A minor controversy arose from its naming process. Tempel had awarded the honour of naming the asteroid to
Carl August von Steinheil
Carl August von Steinheil (12 October 1801 – 14 September 1870) was a German physicist, inventor, engineer and astronomer.
Biography
Steinheil was born in Ribeauvillé, Alsace. He studied law in Erlangen since 1821. He then studied astronomy i ...
in recognition of his achievements in
telescope production. Von Steinheil elected to name it "Maximiliana" after the reigning monarch
Maximilian II of Bavaria. At the time, asteroids were conventionally given classical names, and a number of astronomers protested this contemporary appellation. The name
Cybele was chosen instead, referring to the
Phrygia
In classical antiquity, Phrygia ( ; grc, Φρυγία, ''Phrygía'' ) was a kingdom in the west central part of Anatolia, in what is now Asian Turkey, centered on the Sangarios River. After its conquest, it became a region of the great empires ...
n goddess of the earth.
(The previously discovered
45 Eugenia
Eugenia ( minor planet designation: 45 Eugenia) is a large asteroid of the asteroid belt. It is famed as one of the first asteroids to be found to have a moon orbiting it. It was also the second triple asteroid to be discovered, after 87 Sylvia ...
,
54 Alexandra
Alexandra ( minor planet designation: 54 Alexandra) is a carbonaceous asteroid from the intermediate asteroid belt, approximately 155 kilometers in diameter. It was discovered by German-French astronomer Hermann Goldschmidt on 10 September 1858, ...
, and
64 Angelina had nevertheless also been given non-classical names; 64 Angelina had also been discovered by Tempel, but its name stood despite similar protests.)
Physical characteristics
The first Cybelian stellar
occultation was observed on 17 October 1979, in the
Soviet Union. The asteroid appeared to have an irregular shape, with the longest
chord
Chord may refer to:
* Chord (music), an aggregate of musical pitches sounded simultaneously
** Guitar chord a chord played on a guitar, which has a particular tuning
* Chord (geometry), a line segment joining two points on a curve
* Chord ( ...
being measured as 245 km, closely matching results determined by the IRAS satellite in 1983 ''(see below)''. During the same 1979 occultation, a hint of a possible 11 km wide
minor-planet moon at 917 km distance was detected,
but has since never been corroborated. As of 2017, neither the ''Asteroid Lightcurve Data Base'' nor ''Johnstons archive'' consider ''Cybele'' to be a
binary asteroid.
Diameter estimates
Mean-diameter estimates for ''Cybele'' range between 218.56 and 300.54 kilometers. According to observations by the Infrared Astronomical Satellite
IRAS in 1983, the asteroid has a diameter of 237.26 km.
The
NEOWISE mission of NASA's
Wide-field Infrared Survey Explorer gave a diameter of 218.56 and 276.58 km.
The largest estimates of 300.54 km is from the Japanese
Akari satellite.
In 2004, Müller estimated ''Cybele'' using thermophysical modelling (TPM) to have dimensions of 302 × 290 × 232 km, which corresponds to a mean-diameter of 273.0 km.
Spectrum
Examination of the asteroid's infrared spectrum shows an absorption feature that is similar to the one present in the spectrum of
24 Themis
Themis ( minor planet designation: 24 Themis) is one of the largest asteroids in the asteroid belt. It is also the largest member of the Themistian family. It was discovered by Annibale de Gasparis on 5 April 1853. It is named after Themis, th ...
. This can be explained by the presence of water ice. The asteroid may be covered in a layer of fine silicate dust mixed with small amounts of water-ice and organic solids.
Recent occultations
On August 24, 2008, ''Cybele''
occulted
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 ...
2UCAC 24389317, a 12.7-
magnitude star in the constellation
Ophiuchus which showed a long axis of at least 294 km.
On 11 October 2009, ''Cybele'' occulted a 13.4-magnitude star in the constellation
Aquarius
Aquarius may refer to:
Astrology
* Aquarius (astrology), an astrological sign
* Age of Aquarius, a time period in the cycle of astrological ages
Astronomy
* Aquarius (constellation)
* Aquarius in Chinese astronomy
Arts and entertainment ...
.
Notes
References
External links
Asteroid Lightcurve Database (LCDB) query form
)
Dictionary of Minor Planet Names Google books
at Observatoire de Genève, Raoul Behrend
– Minor Planet Center
*
*
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Discoveries by Wilhelm Tempel
Named minor planets
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