The data on the plate doesn't outright confirm exoplanets in the system, but astronomers are confident that it's only a matter of time before their existence in such systems is confirmed. 

While modern astronomers use digital tools to image stars, that hasn't always been the case. Turn the clock back a century, and stargazers were using glass photographic plates to record stellar spectra, showing a spread of all of the component colors of the light from the distant objects. That information can be used to ascertain a lot of information about a star, including its chemical composition.

The new discovery was made when University College London's Jay Farhi contacted the Carnegie Institute of Science looking for a plate in its archive that showed a star discovered by Dutch-American astronomer Adriaan van Maanen in 1917, known as van Maanen's star.