Aegina (from Latin Aegīna, Aegīnēta),[4] minor planet designation 91 Aegina, is a large main-belt asteroid. It was discovered by a French astronomer Édouard Jean-Marie Stephan on 4 November 1866. It was his second and final asteroid discovery. The first was 89 Julia. The asteroid's name comes from Aegina, a Greek mythological figure associated with the island of the same name.
Discovery | |
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Discovered by | Édouard Stephan |
Discovery date | 4 November 1866 |
Designations | |
MPC designation | (91) Aegina |
Pronunciation | /ɪˈdʒaɪnə/[1] |
Named after | Aegina |
Minor planet category | Main belt |
Adjectives | Aeginetan /iːdʒɪˈniːtən/[2] |
Orbital characteristics | |
Epoch 31 December 2006 (JD 2454100.5) | |
Aphelion | 428.453 Gm (2.864 AU) |
Perihelion | 346.826 Gm (2.318 AU) |
Semi-major axis | 387.640 Gm (2.591 AU) |
Eccentricity | 0.105 |
Orbital period (sidereal) | 1,523.536 d (4.171 yr) |
Average orbital speed | 18.45 km/s |
Mean anomaly | 183.458° |
Inclination | 2.109° |
Longitude of ascending node | 10.806° |
Argument of perihelion | 73.371° |
Physical characteristics | |
Dimensions | 109.8 km |
Mass | 1.4×1018 kg |
Equatorial surface gravity | 0.0307 m/s² |
Equatorial escape velocity | 0.0580 km/s |
Geometric albedo | 0.043 [3] |
Spectral type | C |
Absolute magnitude (H) | 8.84 |
This body is orbiting the Sun with a period of 4.17 years and an eccentricity of 0.105. The orbit of this object brings it to within 4.9 Gm of the dwarf planet Ceres, and the resulting gravitational interaction has been used to produce mass estimates of the latter.[5] The cross-section size of the asteroid is 110 km and it has a rotation period of six hours. The surface coloring of 91 Aegina is very dark and this C-type asteroid has probably a primitive carbonaceous composition. Observation of absorption bands at wavelengths of 0.7 and 3μm indicate the presence of hydrated minerals and/or ice grains on the surface.[6]
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