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| density=3.35 ± 0.33 g/cm³〔 | surface_grav= m/s² | escape_velocity= km/s | rotation=0.1728 d (4.148 h)〔 | spectral_type=M (Tholen)〔 | abs_magnitude=6.45〔 | albedo=0.17〔 | single_temperature=~161 K ''max:'' 240 K (−32 °C) }} 22 Kalliope〔Pronounced 〕 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. ==Characteristics== 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 measured 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 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「22 Kalliope」の詳細全文を読む スポンサード リンク
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