Intracluster light

Diffuse starlight in galaxy clusters comes from stars bound to the cluster’s gravitational potential but not to individual galaxies.

Tidal stripping: The removal of matter from an astronomical object by gravitational forces exerted by a nearby body. Cluster encounters can pull stars from galaxies and add them to the diffuse light.
Galaxy cluster: A gravitationally bound system containing many galaxies, hot gas, and dark matter. Intracluster light is a stellar component of this larger system.
Coma Cluster: A rich galaxy cluster in the constellation Coma Berenices, about 100 megaparsecs from Earth. Its diffuse stellar component has been studied as a prominent example of intracluster light.
Galaxy formation and evolution: The physical processes that form galaxies and change their structure and contents over cosmic time. Different galaxy histories predict different contributions to the cluster’s unbound stars.
Brightest cluster galaxy: The most luminous galaxy in a galaxy cluster, usually located near its gravitational center. Its extended outskirts can blend observationally with intracluster light.
Galaxy harassment: Repeated high-speed encounters and cluster tides that disturb galaxies in dense environments. Frequent encounters can dislodge stars without destroying their parent galaxies.
Surface brightness: The amount of light received or emitted per unit apparent area of an extended source. Its extremely low surface brightness makes intracluster light difficult to detect.
Virgo Cluster: The nearest major galaxy cluster, centered roughly 16.5 megaparsecs from the Milky Way. Its proximity permits detailed studies of stars and planetary nebulae between galaxies.
Cluster merger: The collision and gravitational combination of two or more galaxy clusters. Mergers can redistribute existing diffuse stars and release new ones.
Galaxy halo: The extended region surrounding a galaxy, containing dark matter, stars, and gas. The boundary between a galaxy’s stellar halo and cluster-wide light is not always sharp.

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