Stars of spectral type Am are often members of close binaries with a companion of about the same mass, as is the case for IK Pegasi.

Most Algol variables are quite close binaries, and therefore their periods are short, typically a few days.

These are very close binaries, the components of which are non-spherical due to their mutual gravitation.

Beta Lyrae (β Lyr) variables are extremely close binaries, named after the star Sheliak.

Both components are themselves close binaries.

Her work has had a strong influence in the areas of massive stars and close binaries, especially Wolf-Rayet stars.

At the conclusion of his double star work in 1905, he had discovered and measured 1,327 close binaries.

These observations indicate that giant exoplanets orbiting two stars may be fairly common, occurring in perhaps one percent of close binaries.

These stars are close binaries of spectral types F, G, or K that share a common envelope of material and are thus in contact with one another.

Those two were close binaries where no planets could possibly support life, even if planets had existed.