Final answer:
The mass of a star determines its position on the main sequence. Massive stars have higher temperatures and luminosities, while low-mass stars have lower temperatures and luminosities.
Step-by-step explanation:
The mass of a star determines its position on the main sequence. Massive stars have higher temperatures and luminosities, while low-mass stars have lower temperatures and luminosities. This is illustrated by Figure 21.12, which shows the correlation between star mass and position on the main sequence.
In addition, the structure of main-sequence stars is determined by their total mass and composition. This is a result of astrophysicists' studies of model stars. The H-R diagram can be used to interpret these features.
Therefore, it can be concluded that the main sequence is a sequence of stellar masses, with massive stars at high temperatures and luminosities, and low-mass stars at low temperatures and luminosities.