ALL ABOUT A-TYPE ASTEROID 446 AETERNITAS
The main-belt asteroid Aeternitas (a = 2.79 AU) was discovered in 1899 by Wolf and Schwassmann. Knowledge regarding the physical properties of this object has greatly increased over the past three decades. Inversion techniques using our photometric lightcurves collected over three apparitions yield a refined sidereal rotation period of 15.73743 ± 0.00005 h, and generated a convex-hull shape model of the asteroid. Our results reveal that Aeternitas is a prograde rotator with an angular shape, and is likely a collisional fragment. Accordingly, for mantle material to be exposed the parent asteroid must be fragmented or its interior exposed via collisions. Visible and near-infrared spectra indicate that Aeternitas is an olivine-rich A-type with an ol/(ol+px) ratio of 0.92, with a minor (~8%) pyroxene component. Several inferences of mineral chemistry derived from these spectra suggest Mg-rich olivine compositions, analogous to pallasite meteorites. However, recent results suggest that the R-chondrites are a possible meteorite analog. We performed NEATM thermal modeling utilizing WISE (12 and 22 µm) data, employing refined absolute magnitude and slope parameter values. These results provide new estimates for effective diameter (Deff) 56 ± 3 km, geometric albedo (pv) 0.167 ± 0.030, infrared albedo (pir) 0.403 ± 0.040, and beaming parameter (η) 1.48 ± 0.10 for Aeternitas.