148780 Altjira

148780 Altjira /ælˈtʃɪrə/ is a binary classical Kuiper belt object (cubewano).[2] The secondary, S/2007 (148780) 1, is large compared to the primary, 140 kilometres (87 mi) vs. 160 kilometres (99 mi).[4] The Altjiran lightcurve is quite flat (Δmag<0.10), which is indicative of a "quasi-spherical body with a homogeneous surface".[5]

(148780) Altjira
Altjira and its companion imaged by the Hubble Space Telescope in 2006
Discovery
Discovery siteDeep Ecliptic Survey at Kitt Peak[1]
Discovery date20 October 2001
August 2006 (secondary)[2]
Designations
(148780) Altjira
Pronunciation/ælˈtʃɪrə/
2001 UQ18
Cubewano (DES)[3]
AdjectivesAltjirian
Orbital characteristics[1]
Epoch 13 January 2016 (JD 2457400.5)
Uncertainty parameter 3
Observation arc2539 days (6.95 yr)
Aphelion46.877 AU (7.0127 Tm)
Perihelion41.572 AU (6.2191 Tm)
44.224 AU (6.6158 Tm)
Eccentricity0.059979
294.10 yr (107421 d)
124.29°
0.0033513°/day
Inclination5.2056°
2.0132°
297.71°
Known satellites1
Physical characteristics
Dimensions≈128–200 (primary)[4] and 100–180 km (secondary)
Mass3.952×1018 kg[4]
Mean density
0.5–2.0 g/cm3[4]
0.06–0.14[4]
5.7[1] 5.6,[5] 5.4,[2] or 5.1[2] (primary)
secondary's magnitude difference with primary's: 0.7 ± 0.2[2]

    The satellite's orbit has the following parameters: semi-major-axis, 9904 ± 56 km; period, 139.561 ± 0.047 days; eccentricity, 0.3445 ± 0.0045; and inclination, 35.19 ± 0.19°(retrograde). The total system mass is about 4 × 1018 kg.[4]

    It was named after the Arrernte creation deity, Altjira, who created the Earth during the Dreamtime and then retired to the sky.[1]

    References
    1. "JPL Small-Body Database Browser: 148780 Altjira (2001 UQ18)" (2008-10-02 last obs). Retrieved 26 March 2016.
    2. Johnston's Archive on (148780) Altjira Retrieved 2011-11-29
    3. Marc W. Buie. "Orbit Fit and Astrometric record for 148780". SwRI (Space Science Department). Retrieved 2011-11-29.
    4. Grundy, W. M.; Noll, K. S.; Nimmo, F.; Roe, H. G.; Buie, M. W.; Porter, S. B.; Benecchi, S. D.; Stephens, D. C.; Levison, H. F.; Stansberry, J. A. (2011). "Five new and three improved mutual orbits of transneptunian binaries" (PDF). Icarus. 213 (2): 678. arXiv:1103.2751. Bibcode:2011Icar..213..678G. doi:10.1016/j.icarus.2011.03.012. S2CID 9571163.
    5. Transneptunian objects and Centaurs from light curves
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