4769 Castalia

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4769 Castalia
4769Castalia-P36165BC-crop.gif
Arecibo radar image showing Castalia as a contact binary.
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
Minor planet category 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 (?)
4.095 h[1]
Temperature 216–366 K
Spectral type
S (?)
16.9[1]

The asteroid 4769 Castalia (/kɨˈstliə/ 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[edit]

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]

See also[edit]

References[edit]

  1. ^ a b c d e f g "JPL Small-Body Database Browser: 4769 Castalia (1989 PB)". Jet Propulsion Laboratory. Retrieved 2012-06-17. 
  2. ^ "JPL Close-Approach Data: 4769 Castalia (1989 PB)". Retrieved 2012-06-17. 
  3. ^ "(4769) Castalia Ephemerides for August 1989". NEODyS (Near Earth Objects - Dynamic Site). Retrieved 2012-06-20. 
  4. ^ Dr. Lance A. M. Benner (2013-11-18). "Binary and Ternary near-Earth Asteroids detected by radar". NASA/JPL Asteroid Radar Research. Retrieved 2014-03-01. 

External links[edit]