On the spectrum-luminosity diagram, what group do 98 percent of all stars fall into?

The majority of stars, approximately 98 percent, are classified within the Main Sequence on the spectrum-luminosity diagram. The Main Sequence is a continuous band that stretches from the upper left (hot, luminous stars) to the lower right (cooler, dim stars). This classification reflects the main phase of stellar evolution during which stars spend the bulk of their lifespan, fusing hydrogen into helium in their cores.

Stars on the Main Sequence vary widely in terms of size, temperature, and luminosity, but they all exhibit a common characteristic: they maintain a balance between gravitational forces pulling inward and the outward pressure from nuclear fusion reactions. This balance is critical for the stability of the star over millions to billions of years.

In contrast, other classifications like Red Giants, White Dwarfs, and Supergiants represent specific later evolutionary stages or special types of stars, which are far less numerous than those in the Main Sequence. Red Giants, for example, are evolved stars that have exhausted hydrogen in their cores and have expanded, while Supergiants are even larger and more luminous than Red Giants. White Dwarfs, on the other hand, are remnants of stars that have shed their outer layers and represent another stage of stellar evolution after the main phase