79360 Sila–Nunam

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79360 Sila–Nunam
Sidereal rotation period
12.50995 ± 0.00036 d[11]
0.086+0.026
−0.017[8]
Temperature~42 K (−384 °F)
U−B=0.73[8]
B−V=1.08[8][12]
V−R=0.66[12]±0.04[8]
B−R=1.74[8]
V−I=1.25±0.03[8]
R−J=1.4[8]
V−J=2.06±0.03[8]
J−H=0.38±0.08[8]
V−H=2.45±0.08[8]
21.54–21.78 (2014–2015)
(combined) 5.5,[12]
(individual) 6.2 & 6.3 (diff. = 0.12),[8]
5.2[6]

79360 Sila–Nunam (

provisional designation 1997 CS29) is a cold[9] classical Kuiper belt object (cubewano) and binary system made up of components of almost equal size, called Sila and Nunam, orbiting beyond Neptune in the Solar System. The name of the system is the combined names of the two bodies, Sila and Nunam.[13]

Discovery

Sila–Nunam was discovered on 4 February 1997 by

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 on 5 October 2005.

Name

The two components are named after Inuit deities. Sila "air" (Iñupiaq siḷa [siʎə], Inuktitut sila) is the Inuit god of the sky, weather, and life force. Nuna "earth" (Iñupiaq amn Inuktitut nuna-m [nunəm])[14] is the Earth goddess, in some traditions Sila's wife. Nuna created the land animals and, in some traditions, the Inuit (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 (

mean-motion resonance with Neptune.[10]

Physical characteristics

In 2010, thermal flux from Sila–Nunam in 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 of 250 to 420 km (155 to 260 mi).[10]
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.[15][16] There are no water ice absorption bands in its near-infrared spectrum, which resembles that of Ixion.[17]

Sila–Nunam experiences periodic changes in brightness with the full period, which is equal to the orbital binary period (see below). The light curve is double peaked with the secondary period equal to half of the full period. The rotation of both components of the system is synchronously locked with the orbital motion and both bodies are elongated with their long axes pointing to each other.[11] From 2009 to 2017 Sila–Nunam experienced mutual occultation events.[9]

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 250 km in diameter and Nunam 236 km. Their albedo is about 9%. They orbit at a distance of 2,777 ± 19 km (1,726 ± 12 mi) every 12.51 days:[9][11]

Semi-major axis:  2,777 ± 19 km
Orbital period: 12.50995 ± 0.00036 d
Eccentricity: 0.020 ± 0.015°
Inclination: 103.51 ± 0.39°

Each has apparently been resurfaced with ejecta from impacts on the other.[18]

References

  1. IAU Minor Planet Center. Archived from the original
    on 15 October 2008. Retrieved 2 August 2010.
  2. Eskimo–Aleut languages
    .
  3. ^ "MPEC 2009-R09 :Distant Minor Planets (2009 SEPT. 16.0 TT)". IAU Minor Planet Center. 4 September 2009. Retrieved 4 October 2009.
  4. Marc W. Buie. "Orbit Fit and Astrometric record for 79360"
    (2 February 2009 using 142 observations). SwRI (Space Science Department). Retrieved 4 October 2009.
  5. ^ See Mallon (2000) Inuktitut Linguistics for Technocrats: Morphology
  6. ^ a b c "JPL Small-Body Database Browser: 79360 Sila-Nunam (1997 CS29)" (2014-01-28 last obs). Retrieved 25 March 2016.
  7. 3-sigma
    .)
  8. ^ a b c d e f g h i j k l m "(79360) Sila-Nunam". Wm. Robert Johnston. 11 January 2012. Archived from the original on 19 July 2012. Retrieved 12 January 2012.
  9. ^
    doi:10.1016/j.icarus.2012.04.014
    .
  10. ^
    doi:10.1051/0004-6361/201014683
    .
  11. ^
    doi:10.1016/j.icarus.2014.03.046
    .
  12. ^ a b c Stephen C. Tegler. "Kuiper Belt Object Magnitudes and Surface Color". Archived from the original on 1 September 2006. Retrieved 1 August 2010.
  13. ^ Sila–Nunam Mutual Events (Lowell)
  14. ^ For some reason, Nunam includes the subject/possessive suffix -m, while Sila does not. There is no such distinction in Inuit. E.g. nuna-m-i is 'on land' while sila-m-i is 'outside' ("in the air").
  15. doi:10.1086/431958
    .
  16. doi:10.1051/0004-6361/200912582
    .
  17. doi:10.1051/0004-6361:20040005
    .
  18. ^ Rabinowitz, et al. (2009). "Evidence for Recent Resurfacing of the Binary Kuiper Belt Object 1997 CS29".

External links

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