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If it is impossible to resolve the star as a binary visually, then one method determining whether or not a star is part of a binary pair is through analyzing the light emitted from the star system using a [[spectrograph]], binaries observed this way are known a spectroscopic binaries.

If it is impossible to resolve the star as a binary visually, then one method determining whether or not a star is part of a binary pair is through analyzing the light emitted from the star system using a [[spectrograph]], binaries observed this way are known a spectroscopic binaries.

When a Spectrograph is used to indirectly observe a star, it spreads the light from that star into a full [[spectrum]] of colors superimposed with dark absorption lines. If the star observed in this method is a binary star, the spectrum that is analyzed is from both stars together. If in observing this spectrum, a [[Doppler effect]] is observed over time, that determines there is a binary system.  The Doppler effect is caused when the two stars orbit their common center of mass, one star moves closer to us while its companion moves away.  As this happens, the spectral lines in the spectrum for the star moving close will be blue shifted, while the spectral lines of its companion moving away will be red shifted though the Doppler effect.  As the stars move across out line of site in their orbit, the location of absorption lines or each star will become the same.  As the first star moves away and its companion approaches, the opposite shifting of wavelengths will occur, with the companion star's spectral lines blue shifting as it approaches, while the first star's spectral lines red shift as it moves away in its orbit.<ref>http://csep10.phys.utk.edu/astr162/lect/binaries/spectroscopic.html</ref><ref>http://outreach.atnf.csiro.au/education/senior/astrophysics/binary_types.html#bintypespectro</ref>

When a Spectrograph is used to indirectly observe a star, it spreads the light from that star into a full [[spectrum]] of colors superimposed with dark absorption lines. If the star observed in this method is suspected to be a binary star, the spectrum that is analyzed is from both stars together. If in observing this spectrum, a [[Doppler effect]] is observed over time, that determines there is indeed a binary pair.  The Doppler effect is caused when the two stars orbit their common center of mass, one star moves closer to us while its companion moves away.  As this happens, the spectral lines in the spectrum for the star moving close will be blue shifted, while the spectral lines of its companion moving away will be red shifted though the Doppler effect.  As the stars move across out line of site in their orbit, the location of absorption lines or each star will become the same.  As the first star moves away and its companion approaches, the opposite shifting of wavelengths will occur, with the companion star's spectral lines blue shifting as it approaches, while the first star's spectral lines red shift as it moves away in its orbit.<ref>http://csep10.phys.utk.edu/astr162/lect/binaries/spectroscopic.html</ref><ref>http://outreach.atnf.csiro.au/education/senior/astrophysics/binary_types.html#bintypespectro</ref>

One of the most well known spectroscopic binaries is the star system [[Mizar]].  The star system was already known as a visual binary, when in 1889 it was discovered the primary star Mizar A of the visual binary pair, had its own close companion.  This companion was the first star to be found using spectroscopy.  Later it was observed that Mizar B also had its own spectroscopic companion.

One of the most well known spectroscopic binaries is the star system [[Mizar]].  The star system was already known as a visual binary, when in 1889 it was discovered the primary star Mizar A of the visual binary pair, had its own close companion.  This companion was the first star to be found using spectroscopy.  Later it was observed that Mizar B also had its own spectroscopic companion.