Kalliope ( ;

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 ...

: 22 Kalliope) is a large

M-type asteroid M-type (aka M-class) asteroids are a spectral class of asteroids which appear to contain higher concentrations of metal phases (e.g. iron-nickel) than other asteroid classes, and are widely thought to be the source of iron meteorites. Definition ...

from the

asteroid belt The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, called ...

discovered by J. R. Hind on 16 November 1852. It is named after

Calliope In Greek mythology, Calliope ( ; grc, Καλλιόπη, Kalliópē, beautiful-voiced) is the Muse who presides over eloquence and epic poetry; so called from the ecstatic harmony of her voice. Hesiod and Ovid called her the "Chief of all Muses" ...

, the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

Muse In ancient Greek religion and mythology, the Muses ( grc, Μοῦσαι, Moûsai, el, Μούσες, Múses) are the inspirational goddesses of literature, science, and the arts. They were considered the source of the knowledge embodied in the ...

epic poetry An epic poem, or simply an epic, is a lengthy narrative poem typically about the extraordinary deeds of extraordinary characters who, in dealings with gods or other superhuman forces, gave shape to the mortal universe for their descendants. ...

. It is orbited by a small moon named

Linus Linus, a male given name, is the Latin form of the Greek name ''Linos''. It's a common given name in Sweden. The origin of the name is unknown although the name appears in antiquity both as a musician who taught Apollo and as a son of Apollo who di ...

Characteristics

Kalliope is somewhat elongated, approximately 166 km in

diameter In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid for ...

, and slightly asymmetric, as evidenced by resolved images taken with the VLT at the

European Southern Observatory The European Organisation for Astronomical Research in the Southern Hemisphere, commonly referred to as the European Southern Observatory (ESO), is an intergovernmental organization, intergovernmental research organisation made up of 16 mem ...

. This new diameter, which was measured by observing mutual eclipses of Kalliope and Linus, is 8% smaller than that calculated from

IRAS The Infrared Astronomical Satellite (Dutch: ''Infrarood Astronomische Satelliet'') (IRAS) was the first space telescope to perform a survey of the entire night sky at infrared wavelengths. Launched on 25 January 1983, its mission lasted ten mo ...

observations. The spectrum of Kalliope is an M-type, indicating that its surface may be partially composed of

iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...

–

nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow to ...

metal. The asteroid's density is about 3.4 g/cm³. Since the asteroid is likely to be a

rubble pile In astronomy, a rubble pile is a celestial body that is not a monolith, consisting instead of numerous pieces of rock that have coalesced under the influence of gravity. Rubble piles have low density because there are large cavities between the ...

, accounting for a possible porosity of 20–40% leads to the material density of 4.2–5.8 g/cm³, which means that Kalliope is probably made of a mixture of metal with

silicate In chemistry, 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 al ...

s. Spectroscopic studies have shown, however, evidence of

hydrated Drinking is the act of ingesting water or other liquids into the body through the mouth, proboscis, or elsewhere. Humans drink by swallowing, completed by peristalsis in the esophagus. The physiological processes of drinking vary widely among ot ...

minerals and silicates, which indicate rather a stony surface composition. Kalliope also has a low radar albedo, which is inconsistent with a purely metallic surface. Lightcurve analysis indicates that Kalliope's pole most likely points towards

ecliptic coordinates The ecliptic coordinate system is a celestial coordinate system commonly used for representing the apparent positions, orbits, and pole orientations of Solar System objects. Because most planets (except Mercury) and many small Solar System bodi ...

(β, λ) = (−23°, 20°) with a 10° uncertainty, which gives Kalliope an

axial tilt In astronomy, axial tilt, also known as obliquity, is the angle between an object's rotational axis and its orbital axis, which is the line perpendicular to its orbital plane; equivalently, it is the angle between its equatorial plane and orbi ...

of 103°. Kalliope's rotation is then slightly retrograde. Between 2004 and 2021, 22 Kalliope has been observed to

occult The occult, in the broadest sense, is a category of esoteric supernatural beliefs and practices which generally fall outside the scope of religion and science, encompassing phenomena involving otherworldly agency, such as magic and mysticism a ...

fifteen stars.

Satellite

Kalliope has one known natural satellite, called

or (22) Kalliope I Linus. It is quite large about 28 km in diameter and would be a sizeable asteroid by itself. It orbits about 1100 km from the center of Kalliope, equivalent to about 13.2 Kalliope radii. Linus was discovered on 29 August 2001 by

Jean-Luc Margot Jean-Luc Margot (born 1969) is a Belgian-born astronomer and a UCLA professor who specializes in planetary sciences. Career Margot has discovered and studied several binary asteroids with radar and optical telescopes. His discoveries include ( ...

and

Michael E. Brown Michael E. Brown (born June 5, 1965) is an American astronomer, who has been professor of planetary astronomy at the California Institute of Technology (Caltech) since 2003. His team has discovered many trans-Neptunian objects (TNOs), including ...

, while another team led by William Merline also independently detected the moon 3 days later.

First stellar occultation

On 7 November 2006, the first stellar occultation by the satellite of an asteroid (Linus) was successfully observed by a group of Japanese observers according to a prediction that was made just one day before by Berthier et al. based on more than 5 years of regular observations of Kalliope binary system using

adaptive optics Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effect of incoming wavefront distortions by deforming a mirror in order to compensate for the distortion. It is used in astronomical tele ...

systems on ground-based telescopes. The observed

chords 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 (as ...

of Linus give a unique opportunity to estimate the size of the moonlet which was estimated to 20–28 km.

References

External links

Lightcurve plot of 22 Kalliope
Palmer Divide Observatory, '' B. D. Warner'' (2007)
orbit diagram for Linus

datasheet, johnstonsarchive.net

Robert Johnston, johnstonsarchive.net

Prediction and Reduction of Stellar Occultations of Binary Asteroids * * {{DEFAULTSORT:000022 Background asteroids

Kalliope In Greek mythology, Calliope ( ; grc, Καλλιόπη, Kalliópē, beautiful-voiced) is the Muse who presides over eloquence and epic poetry; so called from the ecstatic harmony of her voice. Hesiod and Ovid called her the "Chief of all Muses". ...

Binary asteroids M-type asteroids (Tholen) X-type asteroids (SMASS) 18521116