Editing Binary star (section)

==={{Anchor|Configuration}}Configuration of the system===<!-- This section is linked from [[Detached binary]] and [[Binary system]]-->
 {{multiple image |direction=vertical |width=220
 | image1   = Binary star system - detached configuration q=3.svg
 | alt1     = Detached binary star system
 | caption1 = Detached
 | image2   = Binary star system - semidetached configuration q=3.svg
 | alt2     = Semidetached binary star system
 | caption2 = Semidetached
 | image3   = Binary star system - contact configuration q=3.svg
 | alt3     = Contact binary star system
 | caption3 = Contact
 |footer=Configurations of a binary star system with a mass ratio of 3. The black lines represent the inner critical Roche equipotentials, the Roche lobes.}}

Another classification is based on the distance between the stars, relative to their sizes:<ref>{{cite web |url=http://mintaka.sdsu.edu/faculty/quyen/node10.html |title=Roche model |first=Q. |last=Nguyen |publisher=San Diego State University |url-status=dead |archive-url=https://web.archive.org/web/20070323212330/http://mintaka.sdsu.edu/faculty/quyen/node10.html |archive-date=2007-03-23 |df=dmy-all}}</ref>

''Detached binaries'' are binary stars where each component is within its [[Roche lobe]], i.e. the area where the [[Gravitation|gravitational pull]] of the star itself is larger than that of the other component. While on the [[main sequence]] the stars have no major effect on each other, and essentially evolve separately. Most binaries belong to this class.

''Semidetached binary stars'' are binary stars where one of the components fills the binary star's Roche lobe and the other does not. In this [[interacting binary star]], gas from the surface of the Roche-lobe-filling component (donor) is transferred to the other, accreting star. The [[mass transfer]] dominates the evolution of the system. In many cases, the inflowing gas forms an [[accretion disc]] around the accretor.

A ''[[contact binary]]'' is a type of binary star in which both components of the binary fill their [[Roche lobe]]s. The uppermost part of the [[stellar atmosphere]]s forms a ''common envelope'' that surrounds both stars. As the friction of the envelope brakes the [[orbital motion]], the stars may eventually [[Stellar collision|merge]].<ref>{{cite journal |arxiv=0705.3444 |title=Galactic distribution of merging neutron stars and black holes |first1=R. |last1=Voss |first2=T.M. |last2=Tauris |journal=[[Monthly Notices of the Royal Astronomical Society]] |volume=342 |issue=4 |pages=1169–1184 |year=2003 |doi=10.1046/j.1365-8711.2003.06616.x |doi-access=free |bibcode=2003MNRAS.342.1169V|s2cid=14768050 }}</ref> [[W Ursae Majoris]] is an example.