10 Hygiea
Hygiea (minor-planet designation: 10 Hygiea) is a major asteroid located in the main asteroid belt. With a mean diameter of between 425 and 440 km and a mass estimated to be 3% of the total mass of the belt, it is the fourth-largest asteroid in the Solar System by both volume and mass, and is the largest of the C-type asteroids (dark asteroids with a carbonaceous surface) in classifications that use G type for 1 Ceres. It is very close to spherical, apparently because it had re-accreted after the disruptive impact that produced the large Hygiean family of asteroids.
VLT-SPHERE image of Hygiea | |
| Discovery | |
|---|---|
| Discovered by | A. de Gasparis |
| Discovery site | Astronomical Observatory of Capodimonte |
| Discovery date | 12 April 1849 |
| Designations | |
MPC designation | (10) Hygiea |
| Pronunciation | /haɪˈdʒiːə/ |
Named after | Hygieia |
Alternative designations | A900 GA |
Minor planet category | Main belt (Hygiea family) |
| Adjectives | Hygiean /haɪˈdʒiːən/ |
| Symbol | (historical astronomical), (modern astrological) |
| Orbital characteristics | |
| Epoch 27 April 2019 (JD 2458600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 170.23 yr (62,175 days) |
| Aphelion | 3.4948 AU |
| Perihelion | 2.7882 AU |
Semi-major axis | 3.1415 AU |
| Eccentricity | 0.1125 |
Orbital period (sidereal) | 5.57 yr (2033.8 days) |
Average orbital speed | 16.76 km/s |
Mean anomaly | 152.18° |
| Inclination | 3.8316° |
Longitude of ascending node | 283.20° |
| 312.32° | |
| Proper orbital elements | |
Proper semi-major axis | 3.14178 AU |
Proper eccentricity | 0.1356 |
Proper inclination | 5.1039° |
Proper mean motion | 64.6218 deg / yr |
Proper orbital period | 5.57088 yr (2034.762 d) |
Precession of perihelion | 128.544 arcsec / yr |
Precession of the ascending node | −96.9024 arcsec / yr |
| Physical characteristics | |
| Dimensions | c/a = 0.94±0.05 450 km × 430 km × 424 km ± 10 km × 10 km × 20 km |
Mean diameter | 433±8 km 434±14 km |
| Mass | (8.74±0.69)×1019 kg (8.32±0.80)×1019 kg (representative) |
Mean density | 2.06±0.20 g/cm3 1.94±0.19 g/cm3 |
Synodic rotation period | 13.82559±0.00005 h |
| 0.063 0.0717 | |
| Temperature | ≈164 K max: 247 K (−26°C) |
| C-type | |
| 9.0 to 11.97 | |
| 5.43 | |
| 0.321″ to 0.133″ | |
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