spectrum binary

A spectrum binary is a binary star system which appears to be a single star since observation (generally) does not resolve it into separate light sources, but its spectrum looks like the blended spectra of two stars. The term indicates one of a number binary-star classes based upon how the star is determined to be binary. Others:

• spectroscopic binary
• astrometric binary
• eclipsing binary
• visual binary

(The term spectroscopic binary is used for a star that has a discernible spectral line showing a varying Doppler shift due to its orbit with a binary companion.)