 Binary and multi @-@ star systems consist of two or more stars that are gravitationally bound and generally move around each other in stable orbits . When two such stars have a relatively close orbit , their gravitational interaction can have a significant impact on their evolution . Stars can form part of a much larger gravitationally bound structure , such as a star cluster or a galaxy . 
 Binary and multi @-@ star systems consist of two or more stars <a href='null_relcl' title='1'><mark>that</mark></a>are gravitationally bound and generally move around each other in stable orbits . When two such stars <a href='got' title='2'><mark>have</mark></a> a relatively close orbit , their gravitational interaction can have a significant impact on their evolution . Stars can form part of a much larger gravitationally bound structure , such as a star cluster or a galaxy . 
Binary and multi @-@ star systems consist of 2 or more stars are gravitationally bound and generally move around each other in stable orbits . When tw2uch stars got a relatively close orbit , their gravitational interaction can have a significant impact on their evolution . Stars can form part of a much larger gravitationally bound structure , such as a star cluster or a galaxy .