229762 Gǃkúnǁʼhòmdímà

**229762 Gǃkúnǁʼhòmdímà**, provisional designation **2007 UK126**, is a trans-Neptunian object and binary system from the extended scattered disc, located in the outermost region of the Solar System. It was discovered on 19 October 2007 by American astronomers Megan Schwamb, Michael Brown, and David Rabinowitz at the Palomar Observatory in California and measures approximately 600 kilometers (400 miles) in diameter. This medium-sized TNO appears to be representative of a class of mid-sized objects under approximately 1000 km that have not collapsed into fully solid bodies. Its 100-kilometer moon was discovered by Keith Noll, Will Grundy, and colleagues with the Hubble Space Telescope in 2008, and named Gǃòʼé ǃHú.

## Names

The name *Gǃkúnǁʼhòmdímà* is from the Juǀʼhoansi (ǃKung) people of Namibia. Gǃkúnǁʼhòmdímà is the beautiful aardvark girl of Juǀʼhoan mythology, who sometimes appears in the stories of other San peoples as a python girl or elephant girl; she defends her people and punishes wrongdoers using *gǁámígǁàmì* spines, a rain-cloud full of hail, and her magical oryx horn. The name "Gǃkúnǁʼhòmdímà" derives from *gǃkún* 'aardvark', *ǁʼhòm mà* 'young woman' and the feminine suffix *dí*. The moon Gǃòʼé ǃHú is named after her horn: it means simply 'oryx' (*gǃòʼé*) 'horn' (*ǃhú*).

In the Juǀʼhoan language, the planetoid and moon names are pronounced [ᶢᵏǃ͡χʼṹ ᵑ̊ǁʰòmdí mà] (listen) and [ᶢǃòˀé ǃʰú] (listen), respectively. Usually, when speaking English, the click consonants in words from Juǀʼhoan and other San languages are simply ignored (much as *Xhosa* is pronounced /ˈkoʊzə/ (*KOH-zə*) rather than [ǁʰosa]), resulting in /ˌɡuːnhoʊmˈdiːmə/ (*GOON-hohm-DEE-mə*) and /ˌɡoʊ.eɪˈhuː/ (*GOH-ay-HOO*) or /ˌɡoʊ.eɪˈkuː/ (*GOH-ay-KOO*).

ASCII renderings of the names would be ⟨G!kun||'homdima⟩ (or ⟨G!kun//'homdima⟩) for the primary and ⟨G!o'e !Hu⟩ or ⟨G!o'e!hu⟩ for the secondary.

## Orbit

Gǃkúnǁʼhòmdímà orbits the Sun at a distance of 37.5–107.9 AU once every 620 years and 2 months (226,517 days; semi-major axis of 72.72 AU). Its orbit has an eccentricity of 0.48 and an inclination of 23° with respect to the ecliptic.

An eccentricity of 0.48 suggests that it was gravitationally scattered into its current eccentric orbit. It will come to perihelion in February 2046, and mutual occultation events with its satellite will begin in late 2050 and last most of that decade. It has a bright absolute magnitude of 3.7, and has been observed 178 times over 16 oppositions with precovery images back to 1982.

## Physical characteristics

Stellar occultation events indicate that Gǃkúnǁʼhòmdímà has an effective (equivalent-sphere) diameter of 600–670 km, but is not spherical. Due to complications from its non-spherical shape, the rotational period cannot be definitely determined from current light-curve data, which has an amplitude of Δm = 0.03 ± 0.01 mag, but the simplest solution is 11.05 hours. It is almost certainly between that and 41 hours. The system mass is (1.36±0.03)×1020 kg, about 2% that of Earth's moon and a bit more than Saturn's moon Enceladus. The moon is unlikely to comprise more than 1% or so of the total. Its geometric albedo is approximately 0.15, and its density approximately 1.

As of June 2018, Mike Brown lists it as highly likely to be a dwarf planet, due to its size. However, Grundy et al. propose that the low density and albedo, combined with the fact that TNOs both larger and smaller – including comets – have a substantial fraction of rock in their composition, indicate that it and similar objects such as 174567 Varda and 120347 Salacia (in the size range of 400–1000 km, with albedos less than ≈0.2 and densities of ≈1.2 g/cm3 or less) may retain a degree of porosity in their physical structure, having never collapsed and possibly differentiated into planetary bodies like higher density or higher albedo (and presumably resurfaced) 90482 Orcus and 50000 Quaoar, or at best are only partially differentiated; such objects would never have been in hydrostatic equilibrium and would not be dwarf planets at present.

## Satellite

Gǃòʼé ǃHú
 Discovery date
 Designation
 Pronunciation
 Semi-major axis
 Eccentricity
 Orbital period
 Inclination
 Mean radius
 Spectral type

Gǃkúnǁʼhòmdímà has one known satellite, **Gǃòʼé ǃHú**, which is one of the reddest known TNOs. Size and mass can only be inferred. The magnitude difference between the two is 3.242±0.039 mag. This would correspond to a difference in diameter of a factor of 4.45±0.08, assuming the same albedo. Red satellites often have lower albedos than their primaries, but that may not be the case with this moon. Such uncertainties do not affect density calculations as the moon has only about 1% the total volume, and so is less important than the uncertainties in the primary's diameter.