 VLT-SPHERE image of Julia. The large crater Nonza, half the diameter of the asteroid, is centered on the upper left quadrant. | |
| Discovery | |
|---|---|
| Discovered by | Édouard Stephan |
| Discovery date | 6 August 1866 |
| Designations | |
| (89) Julia | |
| Pronunciation | /ˈdʒuːliə/[1] |
Named after | Julia of Corsica |
| Main belt | |
| Adjectives | Julian/ˈdʒuːliən/ |
| Orbital characteristics[2] | |
| Epoch 31 July 2016 (JD 2457600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 149.68 yr (54672 d) |
| Aphelion | 3.0202 AU (451.82 Gm) |
| Perihelion | 2.08017 AU (311.189 Gm) |
| 2.55016 AU (381.499 Gm) | |
| Eccentricity | 0.18430 |
| 4.07yr (1487.5d) | |
| 255.367° | |
| 0° 14m 31.272s / day | |
| Inclination | 16.128° |
| 311.563° | |
| 45.461° | |
| Physical characteristics | |
| Dimensions | (89±2)×(80±1)×(62±3) km[3] |
| 140±3 km[3][4] 151±3 km[2] 148±8 km[5] | |
| Flattening | 0.30[a] |
| Mass | (4.3±3.2)×1018 kg[4] (4.3±3.6)×1018 kg[3] (6.7±1.8)×1018 kg[5] |
Meandensity | 3.0±2.2 g/cm3[4] 3.0±2.6 g/cm3[3] 4.0±1.3 g/cm3[5] |
| 11.388336±0.000001 h (0.4745 day)[3] | |
| 0.216 (calculated)[4] 0.1764±0.007[2] 0.176[6] | |
| S | |
| 8.74 to 12.61[7] | |
| 6.37[2] | |
| 0.18" to 0.052" | |
89 Julia is a largemain-beltasteroid that was discovered by French astronomerÉdouard Stephan on 6 August 1866. This was first of his two asteroid discoveries; the other was91 Aegina. 89 Julia is believed to be named after SaintJulia of Corsica. Astellaroccultation by Julia was observed on 20 December 1985.
The spectrum of 89 Julia shows the signature ofsilicate rich minerals with possible indications of an abundant calcicclinopyroxene component. It is classified as anS-type asteroid. The asteroid has an estimated diameter of151.4±3.1 km.[8]Photometry from the Oakley Observatory during 2006 produced alightcurve that indicated asidereal rotation period of11.38±0.01 with anamplitude of0.20±0.02 in magnitude.[9]
89 Julia is the parent body of the eponymousJulia family of asteroids. Observations of 89 Julia by theVLT's SPHERE instrument identified a 'highly probable' crater 70–80 km in diameter and4.1±1.7 km deep in the southern hemisphere as the only visible possible source of the family.[10] The crater was named Nonza by the discoverers, referring to thecommune on the island of Corsica where Saint Julia was born.[11] The excavated volume is on the order of 5,000 to15000 km3. It is hypothesized an impact 30 to 120 million years ago by another body approximately 8 kilometers in diameter may have created the collisional family.
