79360 Sila–Nunam

Discovery

Sila–Nunam was discovered on 4 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 . 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 , Inuktitut sila) is the Inuit god of the sky, weather, and life force. Nuna "earth" (Iñupiaq amn Inuktitut nuna-m ) 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.

Orbit

Sila–Nunam is a dynamically cold classical system (cubewano). It orbits very close to 4:7 mean-motion resonance with Neptune.

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 of 250 to. 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.

Sila–Nunam is very red in visible light and has a flat featureless spectrum in the near-infrared. There are no water ice absorption bands in its near-infrared spectrum, which resembles that of Ixion.

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.

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 every 12.51 days:

:{| class="wikitable" |- |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.

References

References

1. There is no established pronunciation of these names in English, but this is perhaps the easiest way to say them. Depending on dialect and accent, the Inuit language vowels ''i'' and ''u'' may be similar to English ''seal'' and ''noon'' or to ''sill'' and ''nook''. The ''a'' can vary in a way reminiscent of how the 'a' in English "an" does (that is, from the 'a' of ''sofa'' to the 'a' of ''cat''). Likewise, the stressed syllable varies, as [[Inuit languages]] do not have distinctive stress. Thus a wide range of English pronunciations can approximate [[Eskimo–Aleut languages]].
2. See Mallon (2000) [http://www.inuktitutcomputing.ca/Technocrats/ILFT.php#morphology Inuktitut Linguistics for Technocrats: Morphology]
3. "List of Transneptunian Objects". [[IAU Minor Planet Center]].
4. [http://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=1997CS29 JPL Horizons] Observer Location: @sun (Perihelion occurs when deldot changes from negative to positive. Uncertainty in time of perihelion is [[3-sigma]].)
5. (11 January 2012). "(79360) Sila-Nunam". Wm. Robert Johnston.
6. Stephen C. Tegler. "Kuiper Belt Object Magnitudes and Surface Color".
7. [[classical Kuiper belt object]] (cubewano) and [[binary asteroid
8. For some reason, ''Nunam'' includes the [[ergative case. 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").
9. Muller, T.G.. (2010). ""TNOs are Cool": A survey of the trans-Neptunian region I. Results from the Herschel science demonstration phase (SDP)". Astronomy and Astrophysics.
10. Grundy, W.M.. (2005). "Near-Infrared Spectrum of Low-Inclination Classical Kuiper Belt Object (79360) 1997 CS29". The Astronomical Journal.
11. Fornasier, S.. (2009). "Visible spectroscopy of the new ESO large programme on trans-Neptunian objects and Centaurs: final results". Astronomy and Astrophysics.
12. Boehnhardt, H.. (2004). "Surface characterization of 28978 Ixion (2001 KX76)". Astronomy and Astrophysics.
13. W.M. Grundy. (2012). "Mutual events in the Cold Classical transneptunian binary system Sila and Nunam". Icarus.
14. Rabinowitz, et al. (2009). "[http://adsabs.harvard.edu/abs/2009DPS....41.6509R Evidence for Recent Resurfacing of the Binary Kuiper Belt Object 1997 CS29]".