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 Radar of Moshup and Squannit taken at Arecibo Observatory in May 2019 | |
| Discovery | |
|---|---|
| Discovered by | Petr Pravec Lenka Kotková Lance A. M. Benner Steven J. Ostro Jon D. Giorgini Raymond F. Jurgens Jean-Luc Margot Michael C. Nolan |
| Discovery date | May 21, 2001 |
| Orbital characteristics | |
| Periapsis | 2,547 m |
| Apoapsis | 2,549 m |
| Satellite of | 66391 Moshup |
| Physical characteristics | |
| 0.451 ± 0.027 km | |
| Mass | (1.35±0.24)×1011 kg |
Meandensity | 2.8 |
| 0.7259 ± 0.0015 | |
Squannit (officially(66391) Moshup I Squannit, formerly sometimes1999 KW4 Beta) is amoon of thenear-Earth asteroid66391 Moshup. Its estimated diameter is about 450 meters. The moon and its parent asteroid are the closest known binary system to the Sun.
The discovery of Squannite was made by a Czechastronomer team led byPetr Pravec andLenka Kotková (-Šarounová) from theOndřejov suggested by photometric observations on June 19, 2000,[1] which was later confirmed by radar observations from theArecibo Observatory by a team led by Steven J. Ostro until the official discovery on May 21, 2001.[2]
The discovery was announced by theInternational Astronomical Union (IAU) two days later on 23 May 2001. On August 27, 2019, theMinor Planet Center announced, that in analogy to the parent asteroid it was given the nameSquannit, after the wife of Moshup, who was a medicine woman of the Makiawisug (little people) people.
Squannite orbits the commonbarycenter on a right-hand andretrograde, almost circular orbit at an average distance of 2.548 km from the planetoid, which corresponds to 3.9 Moshup radii or 11.3 squannite radii. The moon takes 17 hours 25.2 minutes to complete one orbit, which corresponds to about 259 orbits in a Moshup year. Theorbital eccentricity is 0.0004, the orbit isinclined 156.1° relative to theequator of Moshup. This puts the Moon well within Moshup'sHill sphere of 22 km.
In this binary system, a month lasts 6.3 days.
The observations so far indicate an irregularly shaped, elongated body; the most accurate diameter determination (geometric mean) is 451 ± 27 meters. Regarding the exact dimensions, the most accurate value is 0.571 × 0.463 × 0.349 km. The discovery of the moon had no significant impact on the size determination of the parent asteroid, According to current estimates, this has a size of about 1.3 km. Squannit has about a third of the diameter of Moshup, Therefore, its density of 2.8 g/cm3 is assumed to be much higher than that of Moshup, which is presumably a so-calledrubble pile. Accordingly, Squannit should be more compact than the parent asteroid. Both bodies are believed to have been formed by a collision of a protoasteroid with another asteroid. The differences in composition could be due to the phenomenon oflibration.
Based on the average diameter of 451 meters, this results in a surface area of approximately 0.64 km2 (0.25 sq mi). Squannit is 2.5 magnitudes dimmer than Moshup.
Squannit rotatesbound once on its axis every 17 hours and 25.2 minutes, with its long axis aligned with Moshup. This means that the asteroid completes about 259rotations in one Moshup year.