22 Kalliope
Encyclopedia
22 Kalliope is a large main belt M-type
asteroid
discovered by J. R. Hind
on November 16, 1852. It is named after Calliope
, the Greek
Muse
of epic poetry
. It is orbited by a small moon named Linus
.
, and slightly asymmetric, as evidenced by resolved images taken with the VLT
at the European Southern Observatory
. This new diameter, which was measured by observing mutual eclipses of Kalliope and Linus, is smaller by 8% than that determined by the IRAS
satellite in 1980s.
The spectrum of Kalliope is an M-type
, indicating that its surface may be partially composed of iron
–nickel
metal. The asteroid's density is about 3.4 g/cm3. Since the asteroid is likely to be a rubble pile
, 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
s. Spectroscopic studies have shown, however, evidence of hydrated
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
(β, λ) = (−23°, 20°) with a 10° uncertainty, which gives Kalliope an axial tilt
of 103°. Kalliope's rotation is then slightly retrograde.
, or (22) Kalliope I Linus. It is quite large, being 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 August 29, 2001 by Jean-Luc Margot
and Michael E. Brown
, while another team led by William Merline also independently detected the moon 3 days later.
systems on ground-based telescopes. The observed chords
of Linus give a unique opportunity to estimate the size of the moonlet which was estimated to 20–28 km.
M-type asteroid
M-type asteroids are asteroids of partially known composition; they are moderately bright . Some, but not all, are made of nickel-iron, either pure or mixed with small amounts of stone. These are thought to be pieces of the metallic core of differentiated asteroids that were fragmented by impacts,...
asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...
discovered by J. R. Hind
John Russell Hind
John Russell Hind FRS was an English astronomer.- Life and work :John Russell Hind was born in 1823 in Nottingham, the son of lace manufacturer John Hind, and was educated at Nottingham High School...
on November 16, 1852. It is named after Calliope
Calliope
In Greek mythology, Calliope was the muse of epic poetry, daughter of Zeus and Mnemosyne, and is now best known as Homer's muse, the inspiration for the Odyssey and the Iliad....
, the Greek
Greek mythology
Greek mythology is the body of myths and legends belonging to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. They were a part of religion in ancient Greece...
Muse
Muse
The Muses in Greek mythology, poetry, and literature, are the goddesses who inspire the creation of literature and the arts. They were considered the source of the knowledge, related orally for centuries in the ancient culture, that was contained in poetic lyrics and myths...
of epic poetry
Epic poetry
An epic is a lengthy narrative poem, ordinarily concerning a serious subject containing details of heroic deeds and events significant to a culture or nation. Oral poetry may qualify as an epic, and Albert Lord and Milman Parry have argued that classical epics were fundamentally an oral poetic form...
. It is orbited by a small moon named Linus
Linus (moon)
Kalliope I Linus is an asteroid moon that orbits the large M-type asteroid 22 Kalliope. It was discovered on August 29, 2001, by astronomers Jean-Luc Margot and Michael E. Brown with the Keck telescope. Another team also detected the moon with the Canada-France-Hawaii Telescope on September 2,...
.
Characteristics
Kalliope is somewhat elongated, approximately 166 km in diameterDiameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle...
, and slightly asymmetric, as evidenced by resolved images taken with the VLT
Very Large Telescope
The Very Large Telescope is a telescope operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile. The VLT consists of four individual telescopes, each with a primary mirror 8.2m across, which are generally used separately but can be used together to...
at the European Southern Observatory
European Southern Observatory
The European Southern Observatory is an intergovernmental research organisation for astronomy, supported by fifteen countries...
. This new diameter, which was measured by observing mutual eclipses of Kalliope and Linus, is smaller by 8% than that determined by the IRAS
IRAS
The Infrared Astronomical Satellite was the first-ever space-based observatory to perform a survey of the entire sky at infrared wavelengths....
satellite in 1980s.
The spectrum of Kalliope is an M-type
M-type asteroid
M-type asteroids are asteroids of partially known composition; they are moderately bright . Some, but not all, are made of nickel-iron, either pure or mixed with small amounts of stone. These are thought to be pieces of the metallic core of differentiated asteroids that were fragmented by impacts,...
, indicating that its surface may be partially composed of iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
–nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
metal. The asteroid's density is about 3.4 g/cm3. Since the asteroid is likely to be a rubble pile
Rubble pile
In astronomy, rubble pile is the informal name for an object that is not a monolith, consisting instead of numerous pieces of rock that have coalesced under the influence of gravity...
, 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
Silicate
A silicate is a compound containing a silicon bearing anion. The great majority of silicates are oxides, but hexafluorosilicate and other anions are also included. This article focuses mainly on the Si-O anions. Silicates comprise the majority of the earth's crust, as well as the other...
s. Spectroscopic studies have shown, however, evidence of hydrated
Mineral hydration
Mineral hydration is an inorganic chemical reaction where water is added to the crystal structure of a mineral, usually creating a new mineral, usually called a hydrate....
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
Ecliptic coordinate system
The ecliptic coordinate system is a celestial coordinate system that uses the ecliptic for its fundamental plane. The ecliptic is the path that the sun appears to follow across the celestial sphere over the course of a year. It is also the intersection of the Earth's orbital plane and the celestial...
(β, λ) = (−23°, 20°) with a 10° uncertainty, which gives Kalliope an axial tilt
Axial tilt
In astronomy, axial tilt is the angle between an object's rotational axis, and a line perpendicular to its orbital plane...
of 103°. Kalliope's rotation is then slightly retrograde.
Satellite
Kalliope has one known natural satellite, LinusLinus (moon)
Kalliope I Linus is an asteroid moon that orbits the large M-type asteroid 22 Kalliope. It was discovered on August 29, 2001, by astronomers Jean-Luc Margot and Michael E. Brown with the Keck telescope. Another team also detected the moon with the Canada-France-Hawaii Telescope on September 2,...
, or (22) Kalliope I Linus. It is quite large, being 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 August 29, 2001 by Jean-Luc Margot
Jean-Luc Margot
Jean-Luc Margot is a Belgian-born astronomer and a Professor at UCLA. He specializes in planetary sciences. He was awarded the H. C. Urey Prize by the American Astronomical Society in 2004....
and Michael E. Brown
Michael E. Brown
Michael E. Brown has been a professor of planetary astronomy at the California Institute of Technology since 2003....
, while another team led by William Merline also independently detected the moon 3 days later.
First stellar occultation
On November 7, 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 opticsAdaptive optics
Adaptive optics is a technology used to improve the performance of optical systems by reducing the effect of wavefront distortions. It is used in astronomical telescopes and laser communication systems to remove the effects of atmospheric distortion, and in retinal imaging systems to reduce the...
systems on ground-based telescopes. The observed chords
Chord (astronomy)
In the field of astronomy the term chord typically refers to a line crossing an object which is formed during an occultation event. By taking accurate measurements of the start and end times of the event, in conjunction with the known location of the observer and the object's orbit, the length of...
of Linus give a unique opportunity to estimate the size of the moonlet which was estimated to 20–28 km.
External links
- shape model deduced from lightcurve
- orbit diagram for Linus
- A different VLT image of Kalliope and Linus
- Data sheet at Johnston's Archive, includes some other parameters.
- http://www.imcce.fr/page.php?nav=en/ephemerides/phenomenes/occult/stellarocc.php?query=predoc, Prediction and Reduction of Stellar Occultations of Binary Asteroids.