308 Polyxo

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308 Polyxo
Discovered byA. Borrelly
Discovery date31 March 1891
(308) Polyxo
Named after
Πολυξώ Polyxō
Main belt
AdjectivesPolyxoian /pɒlɪkˈsiən/
Orbital characteristics[2]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc124.63 yr (45,521 d)
Aphelion2.860 AU (427.8 Gm)
Perihelion2.640 AU (394.9 Gm)
2.750 AU (411.4 Gm)
4.56 yr (1,665.5 d)
0° 12m 58.158s / day
Physical characteristics
Dimensions140.69±3.8 km[2]
130 km[3]
12.031 ± 0.009 h (0.50129 ± 0.00038 d)[4]
T[4] (Tholen)

Polyxo (minor planet designation: 308 Polyxo) is a main-belt asteroid that was discovered by A. Borrelly on March 31, 1891, in Marseilles. It is orbiting the Sun at a distance of 2.75 AU with a low orbital eccentricity (ovalness) of 0.04 and a period of 4.56 yr. The orbital plane is tilted at an angle of 4.36° to the plane of the ecliptic.[2]

308 Polyxo is classified as a rare T-type asteroid, with a spectrum that bears some similarity to the Tagish Lake meteorite.[6] A spectral feature at a wavelength of 3.0 μm suggests aqueous alteration of some surface materials.[4] Photometric measurements reported in 1983 give a rotation period of 12.03 hours and a brightness variation of 0.20 in magnitude. The adaptive optics instrument at the W. M. Keck Observatory shows an oblate object with a diameter of 130 km. The size ratio between the major and minor axes is 1.26 ± 0.11.[3] Light curves for this object suggests it has a very irregular shape.[4]

Stellar occultation events were observed for this asteroid during 2000 and 2004. The resulting chords provided cross-section diameter estimates of 144.4 and 117.1 km, respectively.[7]


  1. ^ Webster, Noah (1884), A Practical Dictionary of the English Language
  2. ^ a b c "308 Polyxo". JPL Small-Body Database. NASA/Jet Propulsion Laboratory. Retrieved 11 May 2016.
  3. ^ a b Marchis, F.; et al. (November 2006), "Shape, size and multiplicity of main-belt asteroids. I. Keck Adaptive Optics survey", Icarus, vol. 185, no. 1, pp. 39–63, Bibcode:2006Icar..185...39M, doi:10.1016/j.icarus.2006.06.001, PMC 2600456, PMID 19081813.
  4. ^ a b c d Dotto, E.; et al. (December 2004), "308 Polyxo: ISO-SWS spectrum up to 26 micron", Astronomy and Astrophysics, 427: 1081–1084, Bibcode:2004A&A...427.1081D, doi:10.1051/0004-6361:20041638.
  5. ^ Dotto, E.; et al. (October 2002), "ISO observations of low and moderate albedo asteroids. PHT-P and PHT-S results", Astronomy and Astrophysics, 393: 1065–1072, Bibcode:2002A&A...393.1065D, doi:10.1051/0004-6361:20021190.
  6. ^ Hiroi, Takahiro; Hasegawa, Sunao (March 2003), "Revisiting the search for the parent body of the Tagish Lake meteorite - Case of a T/D asteroid 308 Polyxo", Antarctic Meteorite Research, 16: 176-184, Bibcode:2003AMR....16..176H.
  7. ^ Shevchenko, Vasilij G.; Tedesco, Edward F. (September 2006), "Asteroid albedos deduced from stellar occultations", Icarus, 184 (1): 211–220, Bibcode:2006Icar..184..211S, doi:10.1016/j.icarus.2006.04.006.

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