5. Stars on the main sequence turn into larger, cooler red giants as they age. Star clusters show life stages.
6. Red giants look redder and are luminous due to size and atmosphere.
What are these stars about?
Main sequence stars on the H-R diagram show a progression from hot, luminous stars to cooler, dimmer ones, reflecting their mass and energy production through nuclear fusion. As stars like the Sun exhaust hydrogen in their cores, they become red giants, moving to the diagram's upper right due to expanded, cooler outer layers and increased luminosity.
Star clusters, sharing the same origin but varied in stellar masses, display different evolutionary stages on this diagram. Red giants defy the B-V color index's temperature-luminosity correlation due to their size and atmospheric composition, appearing redder and more luminous than main sequence stars at similar temperatures, leading to their distinct position on the H-R diagram.
Complete question:
Part B: Applying the Rule of Observation to a star cluster
The H-R diagram (Figure 18.15) is a plot of a star cluster. The stars are of the same age, born at the same time, yet born different sizes and luminosities.
5. Explain the evolution of a main sequence star to its life end. Your response should incorporate ideas such as location on the H-R diagram, luminosity, and lifetimes of a star, how clusters are formed, and similar concepts.
6. Explain why a Red Giant star does not follow the B-V rule of Observation. This take conceptual thinking.