10 Hygiea
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Light curve-based 3D-model of 10 Hygiea
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|
| Discovery | |
|---|---|
| Discovered by | A. de Gasparis |
| Discovery date | 12 April 1849 |
| Designations | |
| Pronunciation | /haɪˈdʒiːə/ |
|
Named after
|
Hygieia |
| A900 GA | |
| Main belt (Hygiea family) | |
| Adjectives | Hygiean |
| Orbital characteristics | |
| Epoch 27 June 2015 (JD 2457200.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 163.54 yr (59,732 days) |
| Aphelion | 3.5024 AU |
| Perihelion | 2.7817 AU |
| 3.1421 AU | |
| Eccentricity | 0.1146 |
| 5.57 yr (2034.3 days) | |
|
Average orbital speed
|
16.76 km/s |
| 264.46° | |
| Inclination | 3.8377° |
| 283.41° | |
| 312.10° | |
| Proper orbital elements | |
|
Proper semi-major axis
|
3.1417827 AU |
|
Proper eccentricity
|
0.1356 |
|
Proper inclination
|
5.1039° |
|
Proper mean motion
|
64.621 deg / yr |
|
Proper orbital period
|
5.57094 yr (2034.787 d) |
|
Precession of perihelion
|
128.543 arcsec / yr |
|
Precession of the ascending node
|
−96.902 arcsec / yr |
| Physical characteristics | |
| Dimensions | 530×407×370 ±7 km 431 km (mean) |
| 837,080.744 km2 (323,198.682 sq mi) | |
| Mass | (8.67 ±0.15)×1019 kg |
|
Mean density
|
2.08 ± 0.10 g/cm³ |
|
Equatorial surface gravity
|
0.091 metres per second squared (0.0093 g0) |
|
Equatorial escape velocity
|
0.21 kilometres per second (760 km/h) |
| 27.623 h (1.15 d) | |
| 0.0717 | |
| Temperature | ≈164 K max: 247 K (−26°C) |
| C-type | |
| 9.0 to 11.97 | |
| 5.43 | |
| 0.321″ to 0.133″ | |
10 Hygiea is the fourth-largest asteroid in the Solar System by volume and mass, and it is located in the asteroid belt. With somewhat oblong diameters of 350–500 kilometres (220–310 mi) (217–310 miles) and a mass estimated to be 2.9% of the total mass of the belt, it is the largest of the class of dark C-type asteroids with a carbonaceous surface.
Despite its size, Hygiea appears very dim when observed from Earth. This is due to its dark surface and larger-than-average distance from the Sun. For this reason, many smaller asteroids were observed before Annibale de Gasparis discovered Hygiea on 12 April 1849. At most oppositions, Hygiea has a magnitude that is four magnitudes dimmer than Vesta's, and observing it typically requires at least a 100-millimetre (4 in) telescope. However, while at a perihelic opposition, it can often be observed just with 10x50 binoculars.
On 12 April 1849, in Naples, Italy, astronomer Annibale de Gasparis (age 29) discovered Hygiea. It was the first of his nine asteroid discoveries. The director of the Naples observatory, Ernesto Capocci, named the asteroid. He chose to call it Igea Borbonica ("Bourbon Hygieia") in honor of the ruling family of the Kingdom of the Two Sicilies where Naples was located.
In 1852, John Russell Hind wrote that "it is universally termed Hygiea, the unnecessary appendage 'Borbonica' being dropped" (as well as the final "ia" in favor of just "a"). The name comes from Hygieia, the Greek goddess of health, daughter of Asclepius (Aesculapius for the Romans). The name was occasionally misspelled Hygeia in the 19th century, for example in the Monthly Notices of the Royal Astronomical Society.
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