How Many Vesta-Like Bodies Existed in the Asteroid Belt?

Asteroid 4 Vesta is typically thought to be the parent body of the HED (howardite, eucrite, and diogenite) meteorites due to spectral similarities. The discovery of asteroids far from Vesta with HED-like spectra like (1459) Magnya and HED-like meteorites (e.g., NWA 011) with anomalous oxygen isotopic values compared to typical HEDs is evidence that other Vesta-like bodies formed. We broadly define a Vesta-like body as a differentiated object with a crust composed primarily of low-Ca pyroxene and plagioclase feldspar. We estimate the number of Vesta-like bodies that did form by looking at the astronomical evidence; the oxygen isotopic, chemical, and petrologic evidence; and the iron meteorite evidence. Assuming that fragments of Vesta were scattered from Vesta by giant planet migration, we conservatively estimate that at least two Vesta-like bodies (Vesta and the Magnya parent bodies) existed. From the oxygen isotopic, chemical, and petrologic evidence, we also conservatively estimate that seven Vesta-like bodies formed. Analyses of iron meteorites indicate that there may be as many as 23 Vesta-like bodies (Vesta, 10 magmatic iron groups, South Byron trio, Emsland/Mbosi duo, 10 ungrouped irons). This estimate from iron meteorites is most certainly an overestimation due to the existence of a number of non-HED crustal/mantle fragments that potentially originated from bodies with magmatic iron cores. Using our three estimates as a guide, we predict that there were ~10 Vesta-like bodies (including Vesta) that formed in the early solar system. Only Vesta remains intact with the others being disrupted early in solar system history.