Two–Component Dust in Spherically Symmetric Motion

Two components of spherically symmetric, inhomogeneous dust penetrating each other are introduced as a generalization of the well–known Tolman–Bondi dust solution. The field equations of this model are formulated and general properties are discussed. Special solutions with additional symmetries — an extra Killing– or homothetic vector — and their matching to the corresponding Tolman–Bondi solution are investigated. PACS Numbers: 04.20.Jb, 04.40.Nr