What are the three types of binary star systems?

The three types of binary star systems are visual, spectroscopic, and eclipsing.

Visual binary star systems are those that can be seen as two separate stars through a telescope. These systems have a long orbital period, often taking hundreds or thousands of years to complete one orbit. The stars in visual binary systems can be of different sizes and masses, and their orbital paths can be highly elliptical. To understand more about how these orbits behave, you can read about satellites and orbits.

Spectroscopic binary star systems are those that cannot be visually resolved as two separate stars, but instead are detected by observing the Doppler shift of their spectral lines. As the stars orbit each other, their spectral lines shift back and forth, indicating their motion. Spectroscopic binary systems have shorter orbital periods than visual systems, often taking only a few days or weeks to complete one orbit. For further insight into how the Doppler effect plays a role in these observations, see the page on the Doppler effect in sound and light.

Eclipsing binary star systems are those that are detected by observing their periodic changes in brightness. As the stars orbit each other, they periodically pass in front of each other, causing a decrease in overall brightness. Eclipsing binary systems have orbital periods similar to spectroscopic systems, but can provide more information about the sizes and masses of the stars, as well as their distances from Earth. This method is closely linked to the concept of luminosity, which helps astronomers measure and understand the absolute brightness of stars. Additionally, the shifts in spectral lines observed in these systems can be analogous to spectral redshift, another important astronomical phenomenon.