Spectroscopic binaries

Spectroscopic binaries are binary stars that are too close to be observed as separate stars through a telescope. They were identified by their spectral lines shifting due to their motion relative to Earth.
 Pickering and Vogel United States and Germany 1889 Spectroscopic binaries

Spectroscopic binaries are binary stars that are too close to be observed as separate stars through a telescope. They were identified by their spectral lines shifting due to their motion relative to Earth.