Standard stars A, B, C, and D were simulated for this investigation. In reality, astronomers recognize spectral patterns for 7 major classes of stars. These classes are named O, B, A, F, G, K, and M. Temperatures for stars range from above 30,000°C for Class O stars at the top (brightest in the blue portion of its spectrum) to below 3,900°C for Class M stars at the bottom (brightest in the red portion of its spectrum).

Detailed study of many thousands of stellar spectra is helping scientists develop and refine models of stellar evolution—the processes by which stars of different sizes are formed, live, and eventually die.