Page "W Ursae Majoris variable" Paragraph 0

A W Ursae Majoris variable is a type of eclipsing binary variable star.

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.

They are termed contact binaries because the two stars touch and transfer mass and energy through the connecting neck, although astronomer R. E.

Wilson argues that the term " overcontact " is more appropriate.