 Moshup and its satellite Squannit imaged by theVery Large Telescope's SPHERE instrument[1] | |
| Discovery [2] | |
|---|---|
| Discovered by | LINEAR |
| Discovery site | Lincoln Lab's ETS |
| Discovery date | 20 May 1999 |
| Designations | |
| Pronunciation | /ˈmɒʃʌp/ |
Named after | Maushop (native American legend) |
| 1999 KW4 | |
| Aten · NEO · PHA [2][3] Mercury-crosser Venus-crosser | |
| Orbital characteristics [2] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 19.01 yr (6,942 days) |
| Aphelion | 1.0845AU |
| Perihelion | 0.2000 AU |
| 0.6422 AU | |
| Eccentricity | 0.6886 |
| 0.51yr (188 days) | |
| 359.03° | |
| 1° 54m 54s / day | |
| Inclination | 38.884° |
| 244.91° | |
| 192.62° | |
| Knownsatellites | 1 (Squannit/ˈskwɒnɪt/) |
| Earth MOID | 0.0138 AU · 5.4LD |
| Physical characteristics | |
| Dimensions | 1.532 × 1.495 × 1.347 km[4] |
| 1.317±0.040 km[4] | |
| Mass | (2.49±0.054)×1012 kg[4] |
Meandensity | 1.97±0.24 g/cm3[4] |
| 2.7650h[5] | |
| 0.26(derived)[6] | |
| SMASS = S[2][6] B–V=0.85±0.01[7] V–R=0.44±0.02[7] V–I=0.65±0.03[7] | |
| 16.5[2][6] | |
66391 Moshup/ˈmɒʃʌp/, provisional designation1999 KW4, is abinary asteroid, classified as anear-Earth object andpotentially hazardous asteroid of theAten group, approximately 1.3 kilometers in diameter. It was discovered on 20 May 1999, byLincoln Near-Earth Asteroid Research (LINEAR) at theLincoln Laboratory's Experimental Test Site in Socorro, New Mexico, United States.[3] It is aMercury-crosser that comes extremely close to the Sun at aperihelion of 0.2 AU.
The asteroid orbits the Sun at a distance of 0.2–1.1 AU once every 6.18 months (188 days). Its orbit has aneccentricity of 0.69 and aninclination of 39° with respect to theecliptic.[2] A firstprecovery was taken by2MASS at theFred Lawrence Whipple Observatory in 1998, extending the body'sobservation arc by one year prior to its official discovery observation at Socorro.[3]
As apotentially hazardous asteroid, it has an Earthminimum orbital intersection distance of 0.0138 AU (2,060,000 km), or 5.4lunar distances.[2] On 25 May 2036, it will pass 0.0155 AU (2,320,000 km) from Earth.[8]
Thisminor planet wasnumbered by theMinor Planet Center on 10 September 2003. It was named fromMohegan legend, afterMoshup, a giant who lived in the coastal areas of New England. The asteroid's companion is namedSquannit, after the wife of Moshup and a medicine woman of the Makiawisug (little people). The officialnaming citation was published by theMinor Planet Center on 27 August 2019 (M.P.C. 115894).[9]
In theSMASS classification, the asteroid a characterized as a stonyS-type asteroid.[2]
Moshup has aminor-planet moon orbiting it. The moon, namedSquannit/ˈskwɒnɪt/ and designatedS/2001 (66391) 1, is approximately 360 metres in diameter, and orbits its primary 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 byradar observations from Arecibo, announced on 23 May 2001(also see below).[5][10] Based on radar imaging, Squannit's dimensions are estimated to be595 × 450 × 343 meters.[4]
According to radiometric observations fromArecibo Observatory, the asteroid has an effectivemean diameter of 1.317 kilometers.[4] 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 andMichael C. Nolan.[4]
TheCollaborative Asteroid Lightcurve Link adopts a diameter of 1.3 kilometers and derives analbedo 0.26 with anabsolute magnitude of 16.5.[6]
The shapes of the two bodies and their dynamics are complex.[11] With a dimension of approximately1.42 × 1.36 × 1.18 kilometers for a simple triaxialellipsoid, 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 above, 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",[12] which is now understood to be a very common shape for asteroids in critical rotation,[13] including101955 Bennu and162173 Ryugu.
During 19–27 June 2000, a rotationallightcurve of this asteroid was obtained from photometric observations byPetr Pravec andLenka Šarounová atOndřejov Observatory. Lightcurve analysis gave arotation period of 2.7650 hours with a brightness variation of 0.12magnitude (U=3).[5]
