Editing Protoplanetary disk (section)

{{Distinguish|Protoplanetary nebula}}
{{Short description|Gas and dust surrounding a newly formed star}}
[[File:HL Tau protoplanetary disk.jpg|thumb|[[Atacama Large Millimeter Array]] image of [[HL Tauri]]<ref>{{cite web|url=https://www.bbc.co.uk/news/science-environment-29932609|title=Planet formation captured in photo|publisher=[[BBC]]|date=2014-11-06|author=Johnathan Webb}}</ref><ref>{{cite web|url=https://public.nrao.edu/static/pr/planet-formation-alma.html|title=Birth of Planets Revealed in Astonishing Detail in ALMA's 'Best Image Ever'|publisher=NRAO|date=2014-11-06|url-status=dead|archive-url=https://web.archive.org/web/20141106220622/https://public.nrao.edu/static/pr/planet-formation-alma.html|archive-date=2014-11-06}}</ref>]]

A '''protoplanetary disk''' is a rotating [[circumstellar disc]] of dense gas and dust surrounding a [[stellar evolution|young newly formed]]  star, a [[T Tauri star]], or [[Herbig Ae/Be star]]. The protoplanetary disk may not be considered an [[accretion disk]]; while the two are similar, an accretion disk is hotter and spins much faster; it is also found on [[Black hole|black holes]], not stars. This process should not be confused with the accretion process thought to build up the planets themselves. Externally illuminated photo-evaporating protoplanetary disks are called [[proplyds]].