4769 Castalia
|
|
| Discovery[1] | |
|---|---|
| Discovered by | E. F. Helin Palomar Observatory (675) |
| Discovery date | August 9, 1989 |
| Designations | |
| MPC designation | 4769 Castalia (1989 PB) |
|
Named after
|
Castalia |
| Apollo NEO, PHA[1] Venus-crosser asteroid, Mars-crosser asteroid |
|
| Orbital characteristics[1] | |
| Epoch 14 march 2012 (Uncertainty=0)[1] |
|
| Aphelion | 1.5769 AU (Q) |
| Perihelion | 0.54945 AU (q) |
| 1.0631 AU (a) | |
| Eccentricity | 0..48319 |
| 1.10 yr | |
| 148.73° (M) | |
| Inclination | 8.8882° |
| 325.62° | |
| 121.33° | |
| Known satellites | contact binary |
| Physical characteristics | |
| Dimensions | 1.4 km[1] 1.8×0.8 km |
| Mass | 5.0×1011 kg (?) |
|
Mean density
|
2.1 g/cm³ (?) |
|
Sidereal rotation period
|
4.095 h[1] |
| Temperature | 216–366 K |
|
Spectral type
|
S (?) |
| 16.9[1] | |
The asteroid 4769 Castalia (/kᵻˈsteɪliə/ kə-STAY-lee-ə; previously known by the provisional designation 1989 PB) was the first asteroid to be modeled by radar imaging. It is an Apollo, Mars- and Venus-crosser asteroid. It was discovered on August 9, 1989, by Eleanor F. Helin (Caltech) on photographic plates taken at Palomar Observatory. It is named after Castalia, a nymph in Greek mythology.
General information
On 25 August 1989 Castalia passed 0.0269378 AU (4,029,840 km; 2,504,020 mi)[2] (within eleven lunar distances) of Earth, allowing it to be observed with radar from the Arecibo Observatory by Scott Hudson (Washington State University) and Steven J. Ostro (JPL). The data allowed Hudson et al. to produce a three-dimensional model of the object. During the 1989 passage Castalia peaked at an apparent magnitude of 12.[3]
Castalia has a peanut shape, suggesting two approximately 800-meter-diameter pieces held together by their weak mutual gravity. Since then radar observations of other asteroids have found other contact binaries.[4]
Castalia is a potentially hazardous asteroid (PHA) because its minimum orbit intersection distance (MOID) is less than 0.05 AU and its diameter is greater than 150 meters. The Earth-MOID is 0.0204 AU (3,050,000 km; 1,900,000 mi).[1] Its orbit is well-determined for the next several hundred years.
See also
References
External links
- Lua error in package.lua at line 80: module 'strict' not found.
- NASA Asteroid Radar Search – The 228 Radar-Detected Asteroids: Asteroid 4769 Castalia
