accretion disk

noun

variants or less commonly accretion disc

plural accretion disks also accretion discs

: a disk of usually gaseous matter surrounding a massive celestial object (such as a black hole) in which the matter gradually spirals in toward and accretes onto the object as a result of gravitational attraction

Evans' team studied a supermassive black hole with jets 800 million light-years away named 3C 33. They never found an expected X-ray pattern … which results from light reflecting off the accretion disk.

—Bill Andrews

Most other moons are either captured planetesimals, or they formed along with the planet in a common accretion disc.

—Daniel Herwartz, et al.

Examples of accretion disk in a Sentence

Recent Examples on the Web

Typically, about half the star's matter is ejected outward while the remainder forms a glowing accretion disk—a structure made of gas, dust or other material that spirals inwards—around the black hole, briefly illuminating the cosmos in various wavelengths. —Thomas Westerholm, MSNBC Newsweek, 25 June 2025

The matter falling around the black hole settles into a flattened cloud of gas and dust called an accretion disk, from which material is fed to the central black hole. —Robert Lea, Space.com, 23 June 2025

This could be caused by material rotating away from us in the accretion disk. —John Timmer, Ars Technica, 17 June 2024

Meanwhile, a lower mass object, likely a star, is orbiting very close to the black hole and periodically plows through the accretion disk. —Keith Cooper, Space.com, 9 May 2025

Word History

First Known Use

1972, in the meaning defined above

Rhymes for accretion disk

• videodisc
• basilisk
• bisque
• brisk
• disc
• fisc
• fisk
• frisk
• risk
• whisk