308 Polyxo

308 Polyxo
Orbital diagram
Discovery
Discovered byAlphonse Borrelly
Discovery date31 March 1891
Designations
Pronunciation/pəˈlɪksoʊ/
Named after
Πολυξώ Polyxō
Main belt
AdjectivesPolyxoian /pɒlɪkˈsoʊiən/
Orbital characteristics
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)
Eccentricity0.040003
4.56 yr (1,665.5 d)
70.4189°
0° 12m 58.158s / day
Inclination4.36141°
181.727°
115.501°
Physical characteristics
Dimensions140.69±3.8 km
130 km
Mass(2.50±0.16)×1018 kg (2025)
(3.05±0.26)×1018 kg (2023)
Mean density
2.25 g/cm3 (2025)
2.74±0.25 g/cm3 (2023)
12.031 ± 0.009 h (0.50129 ± 0.00038 d)
0.043±0.002
T (Tholen)
8.17

308 Polyxo is a main-belt asteroid that was discovered by Alphonse Borrelly on 31 March 1891, in Marseille. 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.

308 Polyxo is classified as a rare T-type asteroid, with a spectrum that bears some similarity to the Tagish Lake meteorite. A spectral feature at a wavelength of 3.0 μm suggests aqueous alteration of some surface materials. 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. Light curves for this object suggests it has a very irregular shape.

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.

Notes

  1. ↑ Calculated from its standard gravitational parameter GM = 0.167±0.011 km3/s2.
  2. ↑ Assuming a diameter of 129 km.
  3. ↑ Assuming a diameter of 128.6 ± 1.6 km.

References

  1. ↑ Webster, Noah (1884), A Practical Dictionary of the English Language
  2. 1 2 3 "308 Polyxo". JPL Small-Body Database. NASA/Jet Propulsion Laboratory. Retrieved 11 May 2016.
  3. 1 2 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. 1 2 Fuentes-Muñoz, Oscar; Farnocchia, Davide; Giorgini, Jon D.; Park, Ryan S. (1 December 2025). "Asteroid Mass Estimation by Mutual Perturbations During Close Encounters After Gaia Focused Product Release". The Astronomical Journal. 170 (6): 353. Bibcode:2025AJ....170..353F. doi:10.3847/1538-3881/ae0cc9. ISSN 0004-6256. S2CID 283347135.
  5. 1 2 Li 李, Fan 凡; Yuan 袁, Ye 烨; Fu 傅, Yanning 燕宁; Chen 陈, Jian 健 (1 September 2023). "Dynamical Masses of 20 Asteroids Determined with Gaia DR3 Asteroid Observations". The Astronomical Journal. 166 (3): 93. Bibcode:2023AJ....166...93L. doi:10.3847/1538-3881/ace52b. ISSN 0004-6256. S2CID 260534542.
  6. 1 2 3 4 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.
  7. ↑ 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.
  8. ↑ 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.
  9. ↑ 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.