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]
References
^Webster, Noah (1884), A Practical Dictionary of the English Language
^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.