Final answer:
Astronomers test stellar evolution models using observations of star clusters and the H-R diagram to compare predicted evolutionary tracks with observed star distributions, adjusting models based on how well they align with real-world data.
Step-by-step explanation:
Astronomers test models of stellar evolution primarily by utilizing observations and theoretical calculations. One key method involves plotting the properties of a group of stars on an H-R diagram (Hertzsprung-Russell diagram), which allows researchers to observe the distribution of stars in various evolutionary stages. By comparing observed H-R diagrams of star clusters with the evolutionary tracks predicted by computer models, astronomers can gauge the accuracy of these models and adjust them if necessary. Especially useful are clusters of stars, like globular clusters, that are presumed to have formed around the same time. They offer a snapshot in which stars of different masses are found at different stages of evolution, providing a direct way to test models by the position of the turnoff point from the main sequence.
A series of points calculated on the H-R diagram, known as evolutionary tracks, represent the life changes of a star as it progresses through different stages from the main sequence to becoming a red giant or other subsequent phases. These tracks also show how more massive stars evolve more quickly than their lower-mass counterparts. Thus, by analyzing both the individual evolutionary tracks and the collective charting of stars in clusters at various stages of evolution, astronomers can check the reliability of their models against real-world observations.