79360 Sila–Nunam
| Discovery | |
|---|---|
| Discovered by | Jane X. Luu, David C. Jewitt, Chadwick A. Trujillo, Jun Chen[1] |
| Discovery date | 3 February 1997 |
| Designations | |
| MPC designation | 79360 Sila–Nunam |
| 1997 CS29 | |
| TNO (cubewano)[2][3] | |
| Adjectives | Silaupian, Nunaupian[4] |
| Orbital characteristics[6] | |
| Epoch JD 2457000.5 (9 December 2014) | |
| Aphelion | 44.8772 ±0.0037 AU |
| Perihelion | 43.4182 ±0.0014 AU |
| 44.1476 ±0.0036 AU | |
| Eccentricity | 0.016525 ±0.000052 |
| 293.34 a (107,140 d) | |
| 336.08 ±0.13° | |
| Inclination | 2.237894 ±0.000096 ° |
| 304.32358 ±0.00036° | |
| 216.90 ±0.13° | |
| Known satellites | 1 at 2,780 ± 20 km (1,725 ± 10 mi)[5] |
| Physical characteristics | |
| Dimensions | ≈ 250 km (Sila)[5] ≈ 235 km (Nunam)[5][7] (335 ± 85 km combined)[8] |
| Mass | 1.08±0.02×1019 kg (combined)[5] |
|
Mean density
|
0.72+0.37 −0.22 g/cm3 |
| Albedo | 0.086+0.026 −0.017[5] |
| Temperature | ~42 K (−384 °F) |
|
Spectral type
|
U−B=0.73[5] B−V=1.08[5][9] V−R=0.66[9]±0.04[5] B−R=1.74[5] V−I=1.25±0.03[5] R−J=1.4[5] V−J=2.06±0.03[5] J−H=0.38±0.08[5] V−H=2.45±0.08[5] |
| 21.54–21.78 (2014–2015) | |
| (combined) 5.5,[9] (individual) 6.2 & 6.3 (diff. = 0.12),[5] 5.2[6] |
|
79360 Sila–Nunam is a double classical Kuiper belt object (cubewano) with components of almost equal size, orbiting beyond Neptune in the Solar System. The name of the system is the combined names of the two bodies, Sila and Nunam.[7]
Discovery and name
Sila–Nunam was discovered on 3 February 1997 by Jane X. Luu, David C. Jewitt, Chad Trujillo, and Jun Chen at the Mauna Kea Observatory, Hawaii, and given the provisional designation 1997 CS29. It was resolved as a binary system in Hubble observations of 22 October 2002 by Denise C. Stephens and Keith S. Noll and announced, under the designation S/2005 (79360) 1, on 5 October 2005.
The two components are named after Inuit deities. Sila "spirit" is the Inuit god of the sky, weather, and life force. Nunam "earth" is the Earth goddess, in some traditions Sila's wife. Nunam created the land animals and, in some traditions, the Inuit people (in other traditions Sila created the first people out of wet sand). Sila breathed life into the Inuit.[6]
Orbit
Sila–Nunam is a dynamically cold classical system (cubewano). It orbits very close to 4:7 mean-motion resonance with Neptune.[8]
Physical characteristics
In 2010, thermal flux from Sila–Nunam in the far-infrared was measured by the Herschel Space Telescope. As a result, its size, while it was assumed to be a single body, was estimated to lie within the range 250 to 420 km (155 to 260 mi).[8] Now that it is known to be a binary system, one body 95% the size of the other, the diameters are estimated to be 243 and 230 kilometres (151 and 143 mi).
Sila–Nunam is very red in visible light and has a flat featureless spectrum in the near-infrared.[10][11] There are no water ice absorption bands in its near-infrared spectrum, which resembles that of Ixion.[12]
Double system
Sila and Nunam are so close in size (within 5%) that they may be thought of as a double cubewano. Sila is approximately 243 km in diameter and Nunam 230 km. They orbit at a distance of 2,780 ± 20 km (1,727 ± 12 mi) every 12.51 days:[5]
-
Semi-major axis: 2,780 ± 20 km Orbital period: 12.509 9 ± 0.000 4 d Eccentricity: 0.02 ± 0.02° Inclination: 103.5 ± 0.4°
Each has apparently been resurfaced with ejecta from impacts on the other.[13]
References
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- ↑ See
- ↑ 5.00 5.01 5.02 5.03 5.04 5.05 5.06 5.07 5.08 5.09 5.10 5.11 5.12 5.13 5.14 5.15 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 6.0 6.1 6.2 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 7.0 7.1 Sila – Nunam Mutual Events (Lowell)
- ↑ 8.0 8.1 8.2 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 9.0 9.1 9.2 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Rabinowitz, et al. (2009). "Evidence for Recent Resurfacing of the Binary Kuiper Belt Object 1997 CS29".
