Question

question 15 of 19 a spectroscopic binary is defined as a binary star system in which there are doppler shifts in the light from the system as the stars orbit their common center. the stars, viewed from earth, pass directly in front of each other as they orbit the systems center of mass, resulting in periodic dips in brightness. the two stars are separated enough on the sky that the two stars can be seen directly. image credits: nasa/esa/h. bond - stsci/m. barstow - university of leicester.

Explanation:

A spectroscopic binary is identified by Doppler - shifts in the light from the system as the stars orbit their common center. The second option describes an eclipsing binary, and the third option describes a visual binary.

Answer:

The first option: there are Doppler shifts in the light from the system as the stars orbit their common center.