Abundances of refractory elements in quasars

Abstract

A comparison of previous and new observations of iron, silicon, aluminum, magnesium and carbon lines in quasars with theoretical models shows that the gas-phase abundances of these refractory elements cannot be much less than solar, and that they do not show the order-of-magnitude depletions that are found in planetary nebulae and the interstellar medium. In light of this lack of refractory element depletions, it is suggested that the broad emission-line clouds must be devoid of dust.