 The post – main @-@ sequence evolution of binary stars may be significantly different from the evolution of single stars of the same mass . If stars in a binary system are sufficiently close , when one of the stars expands to become a red giant it may overflow its Roche lobe , the region around a star where material is gravitationally bound to that star , leading to transfer of material to the other . When the Roche lobe is violated , a variety of phenomena can result , including contact binaries , common @-@ envelope binaries , cataclysmic variables , and type Ia supernovae . 
 The post – main @-@ sequence evolution of binary stars may be significantly different from the evolution of single stars of the same mass . If stars in a binary system <a href='drop_aux' title='1'><mark>are</mark></a>sufficiently close , when one of the stars <a href='uninflect' title='2'><mark>expands</mark></a> to become a red giant it may overflow its Roche lobe , the region around a star where material is gravitationally bound to that star , leading to transfer of material to the other . When the Roche lobe is violated , a variety of phenomena can result , including contact binaries , common @-@ envelope binaries , cataclysmic variables , and type Ia supernovae . 
The post – main @-@ sequence evolution of binary stars may b significantly diff from da evolution of single stars of the same mass . If stars in a binary system sufficiently close , when one of tdastars expand to become a red giant it may overflow its Roche lobe , thdaegion around a star where material is gravitationally bound to that star , leading to transfer of material to the other . When thedache lobe is violated , a variety of phenomena can result , including contact binaries , common @-@ envelope binaries , cataclysmic variables , and type Ia supernovae .