22 Kalliope
Kalliope and satellite Linus as seen by the W.M. Keck II telescope in 2010
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Discovery
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| Discovered by | John Russell Hind |
| Discovery date | November 16, 1852 |
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Designations
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| Named after | Calliope |
| Alternate name(s) | none |
| Minor planet category |
Main belt |
| Epoch 2010-Jul-23 (JD 2455400.5) | |
| Aphelion | 479.98 Gm 3.2085 AU |
| Perihelion | 391.03 Gm 2.6139 AU |
| Semi-major axis | 435.09 Gm 2.9112 AU |
| Eccentricity | 0.10213 |
| Orbital period | 1814.3 d (4.97 yr) |
| Average orbital speed | 17.42 km/s |
| Mean anomaly | 282.54° |
| Inclination | 13.703° |
| Longitude of ascending node | 66.17° |
| Argument of perihelion | 355.03° |
| Satellites | Linus |
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Physical characteristics
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| Dimensions | 235×144×124 km[2] 166.2±2.8 km[2] 181 ± 4.6 km (IRAS)[1] |
| Mean radius | 83.1 ± 1.4 km[2] |
| Mass | 8.16 ± 0.26×1018 kg |
| Mean density | 3.35 ± 0.33 g/cm³[2] |
| Equatorial surface gravity | 0.079 m/s² |
| Escape velocity | 0.114 km/s |
| Rotation period | 0.1728 d (4.148 h) [3] |
| Albedo | 0.17[2] |
| Temperature | ~161 K max: 240 K (-32 °C) |
| Spectral type | M [3] |
| Absolute magnitude (H) | 6.45[1] |
22 Kalliope (
/kəˈlaɪ.əpiː/ kə-LY-ə-pee; Greek: Καλλιόπη) 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.
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[edit] Characteristics
Kalliope is somewhat elongated, approximately 166 km in diameter,[2] 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.[2]
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.[2] 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 silicates.[2] Spectroscopic studies have shown, however, evidence of hydrated minerals[4] and silicates,[5] which indicate rather a stony surface composition. Kalliope also has a low radar albedo,[6] 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,[7][8] which gives Kalliope an axial tilt of 103°. Kalliope's rotation is then slightly retrograde.
[edit] Satellite
Kalliope has one known natural satellite, Linus, 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.[2] 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.[6][8]
[edit] 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[9] according to a prediction that was made just one day before by Berthier et al.[10] based on more than 5 years of regular observations of Kalliope binary system using adaptive optics 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.
[edit] References
- ^ a b c "JPL Small-Body Database Browser: 22 Kalliope". 2010-06-02 last obs. http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=22. Retrieved 2010-07-22.
- ^ a b c d e f g h i j Descamps, P.; Marchis, F. et al (2008). "New determination of the size and bulk density of the binary asteroid 22 Kalliope from observations of mutual eclipses". Icarus 196 (2): 578–600. arXiv:0710.1471. Bibcode 2008Icar..196..578D. doi:10.1016/j.icarus.2008.03.014.
- ^ a b PDS lightcurve data
- ^ A.S. Rivkin (2000). "The nature of M-class asteroids from 3-micron observations". Icarus 145 (2): 351–368. Bibcode 2000Icar..145..351R. doi:10.1006/icar.2000.6354.
- ^ D.F. Lupishko (1982). "UBV photometry of the M-type asteroids 16 Psyche and 22 Kalliope". Solar System Research 16: 75.
- ^ a b J.L. Margot & M.E. Brown (2003). "A Low-Density M-type Asteroid in the Main Belt". Science 300 (5627): 1939–1942. Bibcode 2003Sci...300.1939M. doi:10.1126/science.1085844. PMID 12817147.
- ^ M. Kaasalainen (2002). "Models of Twenty Asteroids from Photometric Data". Icarus 159 (2): 369–395. Bibcode 2002Icar..159..369K. doi:10.1006/icar.2002.6907. http://www.rni.helsinki.fi/~mjk/IcarPIII.pdf.
- ^ a b F. Marchis (2003). "A three-dimensional solution for the orbit of the asteroidal satellite of 22 Kalliope". Icarus 165 (1): 112–120. Bibcode 2003Icar..165..112M. doi:10.1016/S0019-1035(03)00195-7.
- ^ M. Soma et al (2006). "'Occulation by Kalliope and Linus". CBET 732: 1. Bibcode 2006CBET..732....1S.
- ^ J. Berthier et al (2004). "'Prediction of stellar occultations by satellite of asteroids". Dps-Aas 32.23: 1142. Bibcode 2004DPS....36.3223B.
[edit] 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.
- [1], Prediction and Reduction of Stellar Occultations of Binary Asteroids.
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