(66391) 1999 KW4

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(66391) 1999 KW4
Asteroid 1994 KW4.jpg
Radar images of 1999 KW4 taken at Goldstone
Discovery [1]
Discovered by LINEAR
Discovery site Lincoln Lab's ETS
Discovery date 20 May 1999
Designations
1999 KW4
Aten · NEO · PHA [1][2]
Mercury-crosser
Venus-crosser
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc 19.01 yr (6,942 days)
Aphelion 1.0845 AU
Perihelion 0.2000 AU
0.6422 AU
Eccentricity 0.6886
0.51 yr (188 days)
359.03°
Inclination 38.884°
244.91°
192.62°
Earth MOID 0.0138 AU · 5.4 LD
Physical characteristics
Dimensions 1.3 km (taken)[3]
1.317±0.040 km[1]
(1.5 x 1.5 x 1.34) km[1]
2.7650 h[4]
9.581±0.019 h[5]
0.26 (derived)[3]
SMASS = S:[1] · S [3]
16.5[1][3]

(66391) 1999 KW4, provisional designation 1999 KW4, is a binary[6] asteroid, classified as a near-Earth object and potentially hazardous asteroid of the Aten group, approximately 1.3 kilometers in diameter. It was discovered on 20 May 1999, by Lincoln Near-Earth Asteroid Research (LINEAR) at the Lincoln Laboratory's Experimental Test Site in Socorro, New Mexico, United States.[2] It is also a Mercury-crosser and the closest known binary system to the Sun with a perihelion of just 0.2 AU.

Orbit

The asteroid orbits the Sun at a distance of 0.2–1.1 AU once every 6.18 months (188 days). Its orbit has an eccentricity of 0.69 and an inclination of 39° with respect to the ecliptic.[1] A first precovery was taken by 2MASS at the Fred Lawrence Whipple Observatory in 1998, extending the body's observation arc by one year prior to its official discovery observation at Socorro.[2]

As a potentially hazardous asteroid, it has an Earth minimum orbital intersection distance of Lua error in Module:Convert at line 1851: attempt to index local 'en_value' (a nil value). which corresponds to 5.4 lunar distances.[1] On 25 May 2036, it will pass Lua error in Module:Convert at line 1851: attempt to index local 'en_value' (a nil value). from Earth.[7]

Physical characteristics

In the SMASS classification, the asteroid a characterized as a S:-type, which fall into the broader type of stony S-type asteroids.[1]

Satellite

Simulated animation of the 1999 KW4 binary system

1999 KW4 has a minor-planet moon orbiting it. The moon, designated S/2001 (66391) 1 is approximately 360 metres in diameter, and orbits its primary in every 16 hours at a mean-distance of 2.6 kilometers. The presence of a companion was suggested by photometric observations made by Pravec and Šarounová and was confirmed by radar observations from Arecibo observations and announced on 23 May 2001 (also see below).[4][6]

Diameter and shape

According to radiometric observations from Arecibo Observatory,[not in citation given] the asteroid has a mean diameter of 1.317 kilometers. The observations were taken 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.[8]

The Collaborative Asteroid Lightcurve Link adopts a diameter of 1.3 kilometers and derives an albedo 0.26 with an absolute magnitude of 16.5.[3]

The shapes of the two bodies and their dynamics are complex.[9] With a dimension of 1.5 x 1.5 x 1.34 kilometers for a simple triaxial ellipsoid, the asteroid has an oblate shape, which is dominated by an equatorial ridge at the body's potential-energy minimum. This bizarre property of the equatorial region means that it is 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. It was the first asteroid to be described as "muffin-shaped",[10] which is now understood to be a very common shape for asteroids in critical rotation,[11] including 101955 Bennu and 162173 Ryugu.

Lightcurves

During 19–27 June 2000, a rotational lightcurve of this asteroid was obtained from photometric observations by Petr Pravec and Lenka Šarounová at Ondřejov Observatory. Lightcurve analysis gave a rotation period of 2.7650 hours with a brightness variation of 0.12 magnitude (U=3).[4]

In September 2016, the most recent and poorly rated rotational lightcurve with a period of 9.581±0.019 hours was obtained by the Spanish amateur astronomer group OBAS (U=1).[5]

Numbering and naming

This minor planet was numbered by the Minor Planet Center on 10 September 2003.[12] As of 2019, it has not been named.[2]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 Lua error in package.lua at line 80: module 'strict' not found.
  2. ↑ 2.0 2.1 2.2 2.3 Lua error in package.lua at line 80: module 'strict' not found.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ 4.0 4.1 4.2 Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ 5.0 5.1 Lua error in package.lua at line 80: module 'strict' not found.
  6. ↑ 6.0 6.1 Lua error in package.lua at line 80: module 'strict' not found.
  7. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  8. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  9. ↑ NASA Jet Propulsion Laboratory Asteroid Radar Research, retrieved May 3, 2007
  10. ↑ CBS News - Scientist: Asteroid To Return In 2036,
  11. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  12. ↑ Lua error in package.lua at line 80: module 'strict' not found.

External links

Template:2019 in space

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