Mass and density of B-type asteroid (702) Alauda

Abstract

Observations with the adaptive optics system on the Very Large Telescope reveal that outer main belt asteroid (702) Alauda has a small satellite with primary to secondary diameter ratio of $\sim$56. The secondary revolves around the primary in 4.9143 $\pm$ 0.007 days at a distance of 1227 $\pm$ 24 km, yielding a total system mass of (6.057 $\pm$ 0.36) $\times$ 10$^{18}$ kg. Combined with an IRAS size measurement, our data yield a bulk density for this B-type asteroid of 1570 $\pm$ 500 kg~m$^{-3}$.Comment: In press, ApJ 2011. 6 pages, 4 figure