A
circumstellar disc (or
circumstellar disk) is a
torus, pancake or ring-shaped accumulation of
matter composed of
gas,
dust,
planetesimals,
asteroids or collision fragments in
orbit around a
star. Around the youngest stars, they are the reservoirs of material out of which planets may form. Around mature stars, they indicate that
planetesimal formation has taken place and around
white dwarfs, they indicate that planetary material survived the whole of stellar evolution. Such a disc can manifest itself in various ways.