The new findings solidly confirm the connection between Vesta and a class of meteorites found on Earth called the Howardite, Eucrite and Diogenite
meteorites, which have the same ratios for these elements.
In addition, samples of howardite and diogenite
meteorites were used for comparison.
He simply wanted to take a close look at a meteorite that researchers had classified as a diogenite.
To his surprise, the mineral composition indicated that the meteorite wasn't a diogenite and couldn't have come from 4 Vesta.
Scientists have several theories about why this is the case and the research team-which included lead author James Day of Scripps Institution of Oceanography and Richard Walker of the University of Maryland-set out to explore these theories by looking at diogenite meteorites.
Examination of the samples determined that the highly siderophile elements present in the diogenite meteorites were present during formation of the rocks, which could only occur if late addition or 'accretion' of these elements after core formation had taken place.
Although Vesta and its family are located between Mars and Jupiter, smaller pieces of these asteroids can be found in meteorite collections on Earth, including most eucrite, howardite and diogenite
This basin appears to have excavated into the mantle of Vesta, exposing material spectrally similar to diogenite
meteorites; Vesta's crust is spectrally similar to eucrite and howardite meteorites, thus confirming that Vesta and its family of asteroids are the source of the howardite-eucrite-diogenite
(HED) family of basaltic achondrite meteorites.
For nearly a decade the stone was considered a diogenite
, a class of igneous meteorites believed to be chips of the asteroid Vesta.
ALH84001 masqueraded for almost a decade as a diogenite
, thought to be a chip off the asteroid 4 Vesta.
The three meteorite types -- the eucrites, howardites and diogenites
-- came from an asteroid big enough for its surface rock to melt, possibly from the heat of radioactive elements inside it, concludes a team headed by Dale P.
The closest matches occur between a group of fine-grained igneous meteorites (called howardites, eucrites, and diogenites
, or collectively HEDs) and Vesta.