66652 Borasisi
Kuiper belt binary
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66652 Borasisi, or as a binary (66652) BorasisiâPabu[7] (provisional designation 1999 RZ253), is a binary classical Kuiper belt object. It was discovered in September 1999 by Chad Trujillo, Jane X. Luu and David C. Jewitt[4] and identified as a binary on 23 August 2003 by K. Noll and colleagues[4] using the Hubble Space Telescope.
 Borasisi and its companion Pabu imaged by the Hubble Space Telescope in 2003 | |
| Discovery | |
|---|---|
| Discovered by | C. Trujillo, J. Luu and D. Jewitt |
| Discovery date | 8 September 1999 |
| Designations | |
| (66652) Borasisi | |
| Pronunciation | /bÉrÉËsiËsi/ |
| 1999 RZ253 | |
| trans-Neptunian object cubewano[1][2] SCATNEAR(?)[3] | |
| Orbital characteristics[4] | |
| Epoch 13 January 2016 (JD 2457400.5) | |
| Uncertainty parameter 3 | |
| Observation arc | 4790 days (13.11 yr) |
| Aphelion | 47.291 AU (7.0746 Tm) |
| Perihelion | 39.819 AU (5.9568 Tm) |
| 43.555 AU (6.5157 Tm) | |
| Eccentricity | 0.085781 |
| 287.45 yr (104991 d) | |
| 60.025° | |
| 0.0034289°/day | |
| Inclination | 0.56319° |
| 84.722° | |
| 194.98° | |
| Known satellites | Pabu /ËpÉËbuË/ (137 km in diameter?)[5] |
| Physical characteristics | |
| 163+33 â66 km (combined) 126+25 â51 km (primary) 105+20 â42 km (secondary)[6] | |
| Mass | (3.433±0.027)Ã1018 kg[7] |
Mean density | 2.1+2.6 â1.2 g/cm3[6] |
| 6.4±1.0 h[6] | |
| 0.236+0.438 â0.77[6] | |
| VâR= 0.646 ± 0.058[6] | |
| 6.121 ± 0.070,[6] 5.9[4] | |
Binary
In 2003 it was discovered that Borasisi is a binary with the components of comparable size (about 100â130 km) orbiting the barycentre on a moderately elliptical orbit.[6][8] The total system mass is about 3.4 Ã 1018 kg.[7]
The companion (66652) Borasisi I, named Pabu, orbits its primary in 46.2888 ± 0.0018 days on an orbit with a semi-major axis of 4528 ± 12 km and an eccentricity 0.4700 ± 0.0018. The orbit is inclined with respect to the observer by about 54° meaning that is about 35° from the pole-on position.[7]
Physical properties
The surface of both components of the BorasisiâPabu system is very red.[6]
Naming
Borasisi is named after a fictional creation deity taken from the novel Cat's Cradle by Kurt Vonnegut.[9] In the book, Borasisi is the Sun and Pabu is the name of the Moon:[10]
- Borasisi, the sun, held Pabu, the moon, in his arms and hoped that Pabu would bear him a fiery child. But poor Pabu gave birth to children that were cold, that did not burn... Then poor Pabu herself was cast away, and she went to live with her favorite child, which was Earth.
Exploration
Around 2005, Borasisi was considered as a target for the proposed New Horizons 2 after a Triton/Neptune flyby.[11]
