Editing Star (section)

====Binary stars====
[[Binary stars]]' evolution may significantly differ from that of single stars of the same mass. For example, when any star expands to become a red giant, it may overflow its [[Roche lobe]], the surrounding region where material is gravitationally bound to it; if stars in a binary system are close enough, some of that material may overflow to the other star, yielding phenomena including [[contact binaries]], [[common envelope|common-envelope]] binaries, [[Cataclysmic variable star|cataclysmic variables]], [[blue stragglers]],<ref>{{cite journal |last1=Leiner |first1=Emily M. |last2=Geller |first2=Aaron |title=A Census of Blue Stragglers in Gaia DR2 Open Clusters as a Test of Population Synthesis and Mass Transfer Physics |journal=The Astrophysical Journal |date=2021-01-01 |volume=908 |issue=2 |page=229 |doi=10.3847/1538-4357/abd7e9 |arxiv=2101.11047 |bibcode=2021ApJ...908..229L |s2cid=231718656 |doi-access=free }}</ref> and [[type Ia supernova]]e. Mass transfer leads to cases such as the [[Algol paradox]], where the most-evolved star in a system is the least massive.<ref>{{cite journal |last1=Brogaard |first1=K. |last2=Christiansen |first2=S. M. |last3=Grundahl |first3=F. |last4=Miglio |first4=A. |last5=Izzard |first5=R. G. |last6=Tauris |first6=T. M. |last7=Sandquist |first7=E. L. |last8=VandenBerg |first8=D. A. |last9=Jessen-Hansen |first9=J. |last10=Arentoft |first10=T. |last11=Bruntt |first11=H. |last12=Frandsen |first12=S. |last13=Orosz |first13=J. A. |last14=Feiden |first14=G. A. |last15=Mathieu |first15=R. |date=2018-12-21 |title=The blue straggler V106 in NGC 6791: a prototype progenitor of old single giants masquerading as young |journal=Monthly Notices of the Royal Astronomical Society |volume=481 |issue=4 |pages=5062–5072 |arxiv=1809.00705 |bibcode=2018MNRAS.481.5062B |doi=10.1093/mnras/sty2504 |doi-access=free |last16=Geller |first16=A. |last17=Shetrone |first17=M. |last18=Ryde |first18=N. |last19=Stello |first19=D. |last20=Platais |first20=I. |last21=Meibom |first21=S.}}</ref>

The evolution of binary star and higher-order [[star system]]s is intensely researched since so many stars have been found to be members of binary systems. Around half of Sun-like stars, and an even higher proportion of more massive stars, form in multiple systems, and this may greatly influence such phenomena as novae and supernovae, the formation of certain types of star, and the enrichment of space with nucleosynthesis products.<ref name="beccari2019">{{cite book |last1=Beccari |first1=Giacomo |url=https://books.google.com/books?id=Um2MDwAAQBAJ |title=The Impact of Binary Stars on Stellar Evolution |last2=Boffin |first2=Henri M. J. |date=2019 |publisher=Cambridge University Press |isbn=978-1-108-42858-3}}</ref>

The influence of binary star evolution on the formation of evolved massive stars such as [[luminous blue variable]]s, Wolf–Rayet stars, and the progenitors of certain classes of [[core collapse supernova]] is still disputed. Single massive stars may be unable to expel their outer layers fast enough to form the types and numbers of evolved stars that are observed, or to produce progenitors that would explode as the supernovae that are observed. Mass transfer through gravitational stripping in binary systems is seen by some astronomers as the solution to that problem.<ref>{{cite journal |bibcode=2017ApJ...840...10Y |title=Type Ib and IIb Supernova Progenitors in Interacting Binary Systems |last1=Yoon |first1=Sung-Chul |last2=Dessart |first2=Luc |last3=Clocchiatti |first3=Alejandro |journal=The Astrophysical Journal |year=2017 |volume=840 |issue=1 |page=10 |doi=10.3847/1538-4357/aa6afe |arxiv=1701.02089 |s2cid=119058919 |doi-access=free }}</ref><ref>{{cite journal |bibcode=2016MNRAS.459.1505M |title=Helium stars: Towards an understanding of Wolf-Rayet evolution |last1=McClelland |first1=L. A. S. |last2=Eldridge |first2=J. J. |journal=Monthly Notices of the Royal Astronomical Society |year=2016 |volume=459 |issue=2 |page=1505 |doi=10.1093/mnras/stw618 |doi-access=free |arxiv=1602.06358 |s2cid=119105982 }}</ref><ref>{{cite journal |bibcode=2020A&A...634A..79S |title=Why binary interaction does not necessarily dominate the formation of Wolf-Rayet stars at low metallicity |last1=Shenar |first1=T. |last2=Gilkis |first2=A. |last3=Vink |first3=J. S. |last4=Sana |first4=H. |last5=Sander |first5=A. A. C. |journal=Astronomy and Astrophysics |year=2020 |volume=634 |pages=A79 |doi=10.1051/0004-6361/201936948 |arxiv=2001.04476 |s2cid=210472736 }}</ref>