![]() | |
Discovery | |
---|---|
Discovered by | John Russell Hind |
Discovery date | 24 June 1852 |
Designations | |
(18) Melpomene | |
Pronunciation | /mɛlˈpɒmɪniː/[1] |
Named after | Melpomenē |
Main belt | |
Adjectives | Melpomenean /mɛlpɒmɪˈniːən/[2] |
Symbol | ![]() |
Orbital characteristics[3] | |
Epoch 13 September 2023 (JD 2453300.5) | |
Aphelion | 2.797 AU (418.4 million km) |
Perihelion | 1.794 AU (268.4 million km) |
2.296 AU (343.5 million km) | |
Eccentricity | 0.21839 |
1,270.62 d (3.48 yr) | |
0.3995° | |
Inclination | 10.132° |
150.36° | |
2023-Sep-11 | |
228.15° | |
Earth MOID | 0.81 AU (121 million km) |
Physical characteristics | |
Dimensions | 170 × 155 × 129 km[4] (150 × 125 km)[5] (150 × 170 km)[6] |
141±2 km[7] 139.594±2.452 km[3] | |
Flattening | 0.19[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] |
0.48221 d (11.57 h)[3][8] | |
0.221 (calculated)[7] 0.223[9] 0.181 ± 0.033[3] | |
S[3] | |
7.5[10] to 12.0 | |
6.35[3] | |
0.23" to 0.059" | |
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]
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 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]
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