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Orbital diagram | |
| Discovery | |
|---|---|
| Discovered by | James Craig Watson |
| Discovery date | 16 August 1873 |
| Designations | |
| (133) Cyrene | |
| Pronunciation | /saɪˈriːniː/[1] |
| Named after | Cyrene (nymph) |
| A873 QA; 1910 NB; 1936 HO; 1948 QC; 1959 UR | |
| Minor planet category | Main belt |
| Adjectives | Cyrenean /saɪrɪˈniːən/, Cyrenian /saɪˈriːniən/[2] |
| Orbital characteristics[3] | |
| Epoch 31 July 2016 (JD 2457600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 142.65 yr (52104 d) |
| |{{{apsis}}}|helion}} | 3.48274 astronomical unit|AU (521.010 Gm) |
| |{{{apsis}}}|helion}} | 2.64706 AU (395.995 Gm) |
| 3.06490 AU (458.503 Gm) | |
| Eccentricity | 0.13633 |
| Orbital period | 5.37 yr (1959.9 d) |
| Average Orbital speed | 17.03 km/s |
| Mean anomaly | 316.166° |
| Mean motion | 0° 11m 1.273s / day |
| Inclination | 7.21561° |
| Longitude of ascending node | 319.066° |
| 289.646° | |
| Earth MOID | 1.64415 AU (245.961 Gm) |
| Jupiter MOID | 1.65199 AU (247.134 Gm) |
| TJupiter | 3.206 |
| Physical characteristics | |
| Dimensions | 66.57±6.0 km |
| Mass | 3.1 × 1017 kg |
| Mean density | 2.0? g/cm3 |
Equatorial surface gravity | 0.0186 m/s² |
Equatorial escape velocity | 0.0352 km/s |
| Rotation period | 12.708 h (0.5295 d)[3] 12.707 h (0.5295 d)[4] |
| Geometric albedo | 0.2563±0.053[3] 0.2563[5] |
| Physics | ~133 K |
| S[5] | |
| Absolute magnitude (H) | 7.98,[3] 7.990[6] |
Cyrene, minor planet designation 133 Cyrene, is a fairly large and very bright main-belt asteroid that was discovered by J. C. Watson on 16 August 1873 in Ann Arbor, Michigan, and named after Cyrene, a nymph, daughter of king Hypseus and beloved of Apollo in Greek mythology.[7] It is classified as an S-type asteroid based upon its spectrum. It is listed as a member of the Hecuba group of asteroids that orbit near the 2:1 mean-motion resonance with Jupiter.[8]
In the Tholen classification system, it is categorized as a stony SR-type asteroid.[9] Photometric observations of this asteroid at the Altimira Observatory in 1985 gave a light curve with a period of 12.707 ± 0.015 hours and a brightness variation of 0.22 in magnitude. This result matches previous measurements reported in 1984 and 2005.[4]