Debris disk

A circumstellar disk of dust and larger solid bodies, replenished mainly by collisions among planetesimals after a star’s protoplanetary gas disk dissipates.

Planetesimal: A solid body formed through accretion in a protoplanetary disk, larger than dust grains and smaller than a planet. Planetesimals are the parent bodies whose collisions replenish the disk’s observable dust.
Infrared astronomy: The study of astronomical objects through their infrared radiation. Warm debris grains emit strongly in infrared wavelengths, exposing disks too faint in visible light.
Vega: A bright A-type star in the constellation Lyra, surrounded by a prominent infrared-emitting debris disk. Its infrared excess supplied one of the first clear signs of a disk around a mature star.
Protoplanetary disk: A gas-rich disk of material surrounding a young star, where planets can form. Unlike a debris disk, it retains abundant primordial gas and supports early planet-building processes.
Debris disk gas: Gas detected in some debris disks, often including carbon monoxide and its photodissociation products. Its origin—primordial survival or release from solids—remains uncertain in many systems.
Collisional cascade: A chain of collisions in which large bodies break into progressively smaller fragments. It converts unseen large bodies into the fine grains detected around many stars.
Submillimeter astronomy: Astronomy using electromagnetic radiation between microwave and infrared wavelengths. Long-wavelength observations trace cold dust and larger grains in outer disk regions.
Fomalhaut: A nearby A-type star with a bright, spatially resolved debris ring. Its eccentric ring and nearby planets make it a benchmark for planet–disk interactions.
Transitional disk: A protoplanetary disk with a depleted central region or other signs of evolving structure. It can resemble a cleared debris system, but often remains part of the gas-rich stage.
Planet–disk interaction: The gravitational and physical effects planets exert on material orbiting within a disk. Disk gaps and eccentric rings can indicate planets, but inferring their properties is not unique.

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