| − | The whirling disk of gas that form around a compact object such as a white dwarf, neutron star or black hole as matter is drawn in.<ref>[http://solarsystem.nasa.gov/dictionary/index.cfm?Display=Dictionary&Letter=A NASA Dictionary].</ref> '''Accretion disks''' are associated in the public mind with [[black hole|black holes]], for the striking pictures they create, as matter is sucked into these astronomical bodies.
| + | An '''accretion disk''' is the term for a rapidly rotating disk of material that forms around a high-mass compact object, often a [[black hole]]. Accretion disks can also be associated with other high mass, compact objects such as [[white dwarf]] stars and [[[neutron stars]].<ref>[http://solarsystem.nasa.gov/dictionary/index.cfm?Display=Dictionary&Letter=A NASA Dictionary].</ref> In order to conserve angular momentum, as material in the disk moves towards the central mass, it's rotational speed increases as does it's temperature. As a result, accretion disks often emit radiation in the [[x-ray]] and [[gamma ray]] portions of the electromagnetic spectrum. |