A population of stars is created with the mass distribution described in the “Stellar Demographics” notes. All stars are created on the main sequence and begin fusing hydrogen to helium at the same time.
Consider only the main sequence in this problem. Do not worry about what happens to the stars after they leave the main sequence.
a) Describe how the main sequence of the population changes with time.
b) Describe how an astronomer observing the population could determine the age of the population.
c) Which group of stars dominates the collective luminosity of the population? How does this change as the population ages?
d) Describe how the color of the starlight emitted collectively by the population changes as the population ages.
Why does the Sun shine the way it does? Give a brief, qualitative description of how hydrostatic equilibrium, the ideal gas law, hydrogen fusion, and the fact that heat flows from hot places to cold places determines the radius, luminosity, and surface temperature of the Sun given its mass and composition.