(66391) 1999 KW4
Simulated animation of 1999 KW4's rotation and moon.
|
|
| Discovery | |
|---|---|
| Discovered by | LINEAR |
| Discovery date | 20 May 1999 |
| Designations | |
| none | |
| Aten asteroid, Mercury-crosser asteroid, Venus-crosser asteroid |
|
| Orbital characteristics[1] | |
| Epoch 13 January 2016 (JD 2457400.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 6238 days (17.08 yr) |
| Aphelion | 1.0845 AU (162.24 Gm) |
| Perihelion | 0.20009 AU (29.933 Gm) |
| 0.64228 AU (96.084 Gm) | |
| Eccentricity | 0.68847 |
| 0.51 yr (188.0 d) | |
|
Average orbital speed
|
37.16 km/s |
| 290.088° | |
| 1.9148°/day | |
| Inclination | 38.884° |
| 244.919° | |
| 192.619° | |
| Earth MOID | 0.0124542 AU (1.86312 Gm) |
| Jupiter MOID | 4.22849 AU (632.573 Gm) |
| Physical characteristics | |
| Dimensions | 1.5 x 1.5 x 1.34 km (primary) |
|
Mean radius
|
0.6585 ± 0.02 km |
| Mass | 2.4×1012 kg |
|
Mean density
|
2.0 g/cm³ |
|
Equatorial surface gravity
|
0–0.000 36 m/s² (variable) |
|
Equatorial escape velocity
|
0.000 72 km/s |
| 2.7645 h (0.11519 d) | |
| 0.15 | |
| Temperature | 250–600 K |
| 16.5 | |
(66391) 1999 KW4 (also written (66391) 1999 KW4) is an Aten and Mercury-crossing binary asteroid[2] discovered by LINEAR in 1999.
1999 KW4 has a moon orbiting it. The moon, designated S/2001 (66391) 1 or "1999 KW4 Beta", is ~360 m in diameter, and orbits 1999 KW4 'Alpha' in 0.758 d (16 hours) at a distance of 2.6 km. The presence of a companion was suggested by photometric observations made June 19–27, 2000 by Petr Pravec and Lenka Šarounová at Observatoř Ondřejov (Ondřejov Observatory)[citation needed] and was confirmed by radar observations from Arecibo Observatory from May 21–23, 2001 by Lance A. M. Benner, Steven J. Ostro, Jon D. Giorgini, Raymond F. Jurgens, Jean-Luc Margot and Michael C. Nolan, announced on May 23, 2001.[2]
The shapes of the two bodies and their dynamics are complex.[3] Among other bizarre properties, the equatorial regions of Alpha are very close to breakup: raising a particle a meter above the surface would put it into orbit. As seen in the image at above right, the gravitational effects between the moon and the asteroid create a gigantic mountain extending in the equatorial plane around the entire asteroid.
On May 25, 2036, it will pass 0.0155 AU (2,320,000 km; 1,440,000 mi) from Earth.[1]
See also[edit]
| Wikimedia Commons has media related to (66391) 1999 KW4. |
References[edit]
- ^ a b "JPL Close-Approach Data: 66391 (1999 KW4)" (2013-05-09 last obs (arc=14.9 yr)). Retrieved 6 April 2016.
- ^ a b Johnston, Robert. "(66391) 1999 KW4". johnstonsarchive.net. Retrieved 29 May 2015.
- ^ NASA Jet Propulsion Laboratory Asteroid Radar Research, retrieved May 3, 2007
- Johnston, Wm. Robert, ed. (66391) 1999 KW4 January 7, 2007, retrieved May 3, 2007
- Margot, Jean-Luc, Radar observations of 1999 KW4 November 1999, retrieved July 2016

