18 Melpomene

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18 Melpomene

18 Melpomene is a large, bright main-belt asteroid that was discovered by J. R. Hind on 24 June 1852,[11] and named after Melpomenē, the Muse of tragedy in Greek mythology. Its historical symbol was a dagger over a star; it is in the pipeline for Unicode 17.0 as U+1CECB 𜻋 ().[12][13]

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18 Melpomene
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Discovery
Discovered byJohn Russell Hind
Discovery date24 June 1852
Designations
(18) Melpomene
Pronunciation/mɛlˈpɒmɪn/[1]
Named after
Melpomenē
Main belt
AdjectivesMelpomenean /mɛlpɒmɪˈnən/[2]
Symbol (historical)
Orbital characteristics[3]
Epoch 17.0 October 2024
(JD 2460600.5)
Aphelion2.796 AU (418.3 million km)
Perihelion1.794 AU (268.4 million km)
2.295 AU (343.3 million km)
Eccentricity0.21827
1,269.91 d (3.48 yr)
113.8711°
Inclination10.132°
150.34°
2023-Sep-11
228.05°
Earth MOID0.81 AU (121 million km)
Jupiter MOID2.70 AU (404 million km)
TJupiter3.543
Physical characteristics
Dimensions170 × 155 × 129 km[4]
(150 × 125 km)[5]
(150 × 170 km)[6]
141±2 km[7]
139.594±2.452 km[3]
Flattening0.19[a]
Mass(4.5±0.9)×1018 kg[7]
3.0×1018 kg[4]
Mean density
3.06±0.62 g/cm3[7]
1.69±0.66 g/cm3[4]
11.57 h (0.48 d)[3]
11.570306±0.000005 h[7]
11.573 h (0.48 d)[8]
64°[7]
19°±[7]
12°±[7]
0.221 (calculated)[7]
0.223[9]
0.181 ± 0.033[3]
S[3][7]
7.5[10] to 12.0
6.35[3]
6.51[7]
0.23" to 0.059"
    Close

    Melpomene is classified as an S-type asteroid and is composed of silicates and metals. This asteroid is orbiting the Sun at a distance of 2.296 AU with a period of 3.48 years and an eccentricity (ovalness) of 0.22. The orbital plane is tilted at an angle of 10.1° to the plane of the ecliptic.[3]

    Melpomene occulted the star SAO 114159 on 11 December 1978. A possible Melpomenean satellite with a diameter of at least 37 km was detected. The satellite candidate received a provisional designation S/1978 (18) 1.[14] In 1988 a search for satellites or dust orbiting this asteroid was performed using the UH88 telescope at the Mauna Kea Observatories, but the effort came up empty.[15] Melpomene was observed with the Hubble Space Telescope in 1993. It was able to resolve the asteroid's slightly elongated shape, but no satellites were detected.[5]

    Melpomene has been studied by radar.[16] Photometric observations during 2012 provided a rotation period of 11.571±0.001 h with a brightness variation of 0.34±0.02 in magnitude, which is consistent with previous studies.[17] It has a mean diameter of 141±2 km.[7][3]

    Melpomene can reach an apparent magnitude of +7.9 at a favorable opposition near perihelion, such as occurred in September 2002 when it was 0.814 AU (121.8 million km; 317 LD) from Earth.[18]

    Notes

    1. Flattening derived from the maximum aspect ratio (c/a): , where (c/a) = 0.81±0.06.[7]

    References

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