Accretiondisk

An accretion disk (also spelled accretion disc) is a structure formed by diffuse material in orbital motion around a central body, where the central body is typically a star, black hole, protostar, or white dwarf. The material within the disk is drawn towards the central body through gravitational attraction, with the disk itself forming due to the conservation of angular momentum. This process is known as accretion, and the disk is where the material accumulates before falling onto the central body. Accretion disks are commonly found in various astrophysical systems, such as active galactic nuclei, quasars, and protoplanetary systems. In Hebrew, an accretion disk is called דיסקית צבירה. In other languages, it is referred to as Akretionsscheibe in German, disco de acreción in Spanish, and disque d'accrétion in French. The study of accretion disks is crucial for understanding the growth and evolution of celestial objects, as well as the dynamics of matter in strong gravitational fields.