  Although the existence of a faint background of starlight in the core of the
Coma cluster has been well established (1,2), its origin is uncertain. This
vast sea of stars could have formed outside the galaxies, using gas left over
from the time of the cluster's birth. Alternatively, it might be the
accumulated debris generated by interactions between the galaxies over the
lifetime of the cluster (3). Here we report the discovery of three large, low
surface brightness features in the Coma cluster; the most spectacular is a
plume-like structure, 130 kpc long, in the cluster's heart. These structures
will disperse over the next one to two billion years, thereby enhancing the
general background light. If this epoch is typical, we argue that a significant
fraction -- perhaps even most -- of the intracluster light results from a
steady accumulation of tidal debris generated during galaxy-galaxy and
galaxy-cluster interactions.
