Pabu (moon)
| (66652) Borasisi I (Pabu) | |
|---|---|
| Provisional or systematic name | S / 2003 (66652) 1 |
| Central body | (66652) Borasisi |
| Properties of the orbit | |
| Major semi-axis | (4660 ± 170) km |
| Periapsis | 2516 km |
| Apoapsis | 6804 km |
| eccentricity | 0.460 ± 0.013 |
| Orbit inclination | (152.0 ° ± 3) (ecliptic) ° |
| Orbital time | (46.263 + 0.006 / -0.074) d |
| Mean orbital velocity | 0.0037 km / s |
| Physical Properties | |
| Albedo | ≈ 0.12 to 0.17 |
| Medium diameter | ≈ 137 km |
| Dimensions | ≈ (1.34 ± 0.27) 10 18 kg |
| Medium density | ≈ 1.0 g / cm 3 |
| Acceleration of gravity on the surface | ≈ 0 m / s 2 |
| Escape speed | ≈ 0 m / s |
| discovery | |
| Explorer |
|
| Date of discovery | April 23, 2003 |
| Remarks | Smaller component of a double asteroid. |
Pabu is the smaller component ( moon ) of the double asteroid system of the Kuiper belt - asteroids and Cubewanos (66652) Borasisi . Its mean diameter is around 134 kilometers, making it only around 17.5% smaller than the mother asteroid .
Discovery and naming
Pabu was on April 23, 2003 by Keith S. Noll, Denise C. Stephens, Dale Cruikshank, Will M. Grundy, William Roma Nisshin and Stephen C. Tegler with observations using the infrared - spectrometer of the Hubble Space Telescope discovered. On November 9, 2001, Hubble observations already vaguely indicated a companion. Pabu was found at a distance of 0.21 ± 0.02 arc seconds from the Borasisi, which had been discovered four years earlier, from which a distance between the two bodies of 6300 km ± 600 km was initially calculated. The discovery was announced on June 6, 2003; the companion was given the provisional designation S / 2003 (66652) 1 .
The Borasisi and Pabu systems are the first asteroids of the Kuiper Belt , which was not named after a real existing mythology. Like Borasisi, Pabu as a term for moon comes from the fictional religion of "Bokononismus" in Kurt Vonnegut's novel Katzenwiege ( Cat's Cradle , 1963). The moon was given the name Pabu to match the naming of the main body.
Track properties
Pabu orbits Borasisi in a retrograde , very elliptical orbit between 2516 and 6804 km from its center (major orbit half-axis 4660 km or around 56.1 Borasisi and 68.0 Paburadien). Since both revolve around the common center of gravity , the system is to be understood as a double asteroid system. The orbital eccentricity is 0.460, the web is 152.0 ° to the ecliptic inclined .
Pabu and Borasisi orbit each other in 46 days, 6 hours and 18.7 minutes, which corresponds to about 2,274.2 orbits in a Borasisi year (around 288.05 earth years).
Physical Properties
Pabu has an estimated diameter of 137 km (about 82.5% of the central body), based on the assumed equal reflectivity of 12-17% for Borasisi. The surface is therefore relatively dark. Like Borasisi, its density is estimated at around 1.0 g / cm 3 . It can therefore be assumed that Pabu is porous on the inside and belongs to the Rubble Piles . Another possibility would be a high water ice deposit .
exploration
Since its discovery in 2003, Pabu has been observed through the Hubble Space Telescope as well as through terrestrial telescopes and its orbital elements have been determined.