22 Kalliope
Kalliope and satellite Linus as seen by the W.M. Keck II telescope in 2010
|
|
| Discovery | |
|---|---|
| Discovered by | John Russell Hind |
| Discovery date | November 16, 1852 |
| Designations | |
| Pronunciation | /kəˈlaɪ.əpiː/ kə-LY-ə-pee |
|
Named after
|
Calliopē |
| none | |
| Main belt | |
| Orbital characteristics | |
| Epoch 2010-Jul-23 (JD 2455400.5) | |
| Aphelion | 479.98 Gm 3.2085 AU |
| Perihelion | 391.03 Gm 2.6139 AU |
| 435.09 Gm 2.9112 AU |
|
| Eccentricity | 0.10213 |
| 1814.3 d (4.97 yr) | |
|
Average orbital speed
|
17.42 km/s |
| 282.54° | |
| Inclination | 13.703° |
| 66.17° | |
| 355.03° | |
| Known satellites | Linus |
| Physical characteristics | |
| Dimensions | 235×144×124 km 166.2±2.8 km 181 ± 4.6 km (IRAS) |
|
Mean radius
|
83.1 ± 1.4 km |
| Mass | 8.16 ± 0.26×1018 kg |
|
Mean density
|
3.35 ± 0.33 g/cm³ |
| 0.079 m/s² | |
| 0.114 km/s | |
| 0.1728 d (4.148 h) | |
| Albedo | 0.17 |
| Temperature | ~161 K max: 240 K (−32 °C) |
|
Spectral type
|
M (Tholen) |
| 6.45 | |
22 Kalliope is a large M-type asteroid from the asteroid belt 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.
Kalliope is somewhat elongated, approximately 166 km in diameter, 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 8% smaller than that calculated from IRAS observations.
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 silicates. 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.
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. 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.
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