As a star ages, it moves off its original position in the HR diagram
(on the main sequence). Both the path a star takes and the speed with
which it moves depend on its initial mass. With this interactive you can
watch stars of different masses evolve, and see how their temperature,
luminosity and size change with time. Here are the steps you need to
follow:
1. Use the mass slider bar to choose the mass of your star (the units
are Solar Masses).
2. Use the speed slider bar to choose how fast you want "simulated"
time to run. Do you want millions or billions of simulated years to pass
each second?
3. Hit "Create a Star" to start the evolution of the star. Notice that
the size of the star is shown in the box on the lower right hand
corner.
4. You can always go back to view the evolution of a star you have
already seen by clicking on the drop down mass window and hitting "redraw":
The life slider bar lets you move back and forth along the star’s
evolutionary path.