_Adrastea.png) 3D model based on lightcurve data | |
| Discovery | |
|---|---|
| Discovered by | Johann Palisa |
| Discovery date | 18 August 1884 |
| Designations | |
| (239) Adrastea | |
| Pronunciation | /ædrəˈstiːə/ |
Named after | Adrasteia |
| A884 QA, 1915 TD 1955 MK1, 1956 UJ | |
| Main belt | |
| Orbital characteristics[1] | |
| Epoch 31 July 2016 (JD 2457600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 131.66 yr (48,087 d) |
| Aphelion | 3.66279 AU (547.946 Gm) |
| Perihelion | 2.2695 AU (339.51 Gm) |
| 2.96616 AU (443.731 Gm) | |
| Eccentricity | 0.23486 |
| 5.11 yr (1,865.9 d) | |
Average orbital speed | 17.25 km/s |
| 233.617° | |
| 0° 11m 34.584s / day | |
| Inclination | 6.1746° |
| 180.634° | |
| 210.15° | |
| Physical characteristics | |
| Dimensions | 41.52±1.4 km[1] |
| 18.4707 h (0.76961 d)[1] | |
| 0.0777±0.006[1] | |
| Temperature | unknown |
| unknown | |
| 10.4[1] | |
239 Adrastea is a main belt asteroid. It was discovered by Johann Palisa on 18 August 1884 in Vienna, and was named after the Greek nymph Adrasteia. This asteroid is orbiting the Sun at a distance of 2.97 AU with a period of 5.11 years and an eccentricity (ovalness) of 0.23. The orbital plane is tilted at an angle of 6.17° to the plane of the ecliptic.[1]
Photometric data collected during 2009 were used for light curve analysis of this asteroid, yielding a rotation period of 18.48±0.03 h with a brightness variation of 0.45±0.05 in magnitude. The result is close to the 18.347±0.003 h period from a study performed in 2003.[2] The asteroid is roughly 42 km in diameter.[1]