White Dwarf Migration in Globular Cluster 47 Tucanae
This diagram shows how white dwarfs, the burned-out relics of stars, are distributed in the ancient globular star cluster 47 Tucanae. The youngest white dwarfs are the hottest and bluest stars dwelling mostly in the cluster's core, where the most massive stars reside. Shortly before collapsing to become white dwarfs, the stars shed most of their mass. Now, as lightweight white dwarfs, they interact gravitationally with more massive stars in the core. Through these gravitational encounters, the white dwarfs rob enough speed from their more massive cousins to begin migrating slowly outward from their home. During their journey, they become older and cooler white dwarfs, depicted in the orange dots. Eventually, the white dwarfs settle on the outskirts of the cluster, where the oldest, coolest, reddest white dwarfs reside.