Final answer:
The absorption spectra of a star system can determine if it is a binary pair of stars by analyzing the colors in the spectrum and studying the shifts in the absorption lines caused by the Doppler effect.
Step-by-step explanation:
The absorption spectra can determine if a star system is a binary pair of stars by analyzing the colors in the spectrum. When a star system is a binary pair, the spectra of the stars show characteristic patterns and shifts in the colors of the absorption lines. These shifts occur due to the Doppler effect as the stars orbit each other, causing changes in the wavelengths of the light they emit. By studying these shifts and patterns, astronomers can identify binary star systems.