{{Short description|Type of galactic form}} {{Refimprove|date=February 2017}} [[File:NGC 253 Galaxy.jpg|thumb|The Sculptor Galaxy (NGC 253) is a disk galaxy.]]
A '''disc galaxy''' (or '''disk galaxy''') is a galaxy characterized by a galactic disc. This is a flattened circular volume of stars that are mainly orbiting the galactic core in the same plane,<ref>{{cite web |title=Disk Galaxies {{!}} COSMOS |url=https://astronomy.swin.edu.au/cosmos/D/Disk+Galaxies |website=astronomy.swin.edu.au}}</ref> although not always in the same direction.<ref>{{cite journal | title=Counter-Rotating Populations in a Disk Galaxy | last=Kuijken | first=Konrad | journal=Publications of the Astronomical Society of the Pacific | volume=105 | page=1016 | date=September 1993 | doi=10.1086/133275 | bibcode=1993PASP..105.1016K }}</ref><ref>{{cite journal | title=Detectability of large-scale counter-rotating stellar disks in galaxies with integral-field spectroscopy | last1=Rubino | first1=M. | display-authors=etal | journal=Astronomy & Astrophysics | volume=654 | at=id. A30 | date=October 2021 | doi=10.1051/0004-6361/202140702 | arxiv=2107.02226 | bibcode=2021A&A...654A..30R }}</ref> These galaxies may or may not include a central non-disc-like region (a galactic bulge).<ref>{{cite web |title=The Galactic Bulge |url=http://burro.case.edu/Academics/Astr222/Galaxy/Structure/bulge.html |website=burro.case.edu}}</ref> They will typically have an orbiting mass of gas and dust in the same plane as the stars. (A lenticular galaxy may be former spiral galaxy from which much of the gas and dust has been stripped.<ref>{{cite journal | title=Lenticular Galaxies and their Environments | last=van den Bergh | first=Sidney | journal=The Astrophysical Journal | volume=702 | issue=2 | pages=1502–1506 | date=September 2009 | doi=10.1088/0004-637X/702/2/1502 | arxiv=0907.3715 | bibcode=2009ApJ...702.1502V }}</ref>) Interactions with other nearby galaxies can perturb and stretch the galactic disk, sometimes completely disrupting the disk.<ref>{{cite journal | title=On the survival and destruction of spiral galaxies in clusters | last1=Moore | first1=Ben | display-authors=etal | journal=Monthly Notices of the Royal Astronomical Society | volume=304 | issue=3 | pages=465–474 | date=April 1999 | doi=10.1046/j.1365-8711.1999.02345.x | arxiv=astro-ph/9811127 | bibcode=1999MNRAS.304..465M }}</ref>
Disc galaxy types include: * Spiral galaxies: ** Unbarred spiral galaxies: (types S, SA) ** Barred spiral galaxies: (type SB) ** Intermediate spiral galaxies: (type SAB) * Lenticular galaxies: (types E8, S0, SA0, SB0, SAB0)
Galaxies that are not disc types include: * Elliptical galaxies: (type dE) * Irregular galaxies: (type dI)
== See also ==
* Thick disk * Thin disk
==References== {{Reflist}}
{{Galaxy}} {{Portal bar|Stars|Outer space}} {{DEFAULTSORT:Disc Galaxy}} Category:Morphological types of galaxy