H-R Diagram (279.0K)
Manipulate the properties of a star (luminosity and temperature) and see how the star evolves along its evolutionary path at a rate determined by its nuclear burning timescale. As the star evolves, its color and size will change.
As the masses of stars were derived from studies of binary systems, it was soon found that mass played the most important role in predicting where the young star would begin its main sequence life.
Stars exist over a fairly limited range of masses; if too massive, their great energy tears them apart into a cluster rather than a single body, and if too small, their gravity is not enough to ignite fusion, and they form brown dwarfs and not main sequence stars.
Why is the main sequence main? There must be some common property that links the diversity of stars we find along the main sequence together into this continuum.
We can use our examination of the H-R diagram to go beyond the simple main sequence hydrogen to helium stage, to more complex evolution into the giant phase when many different fusion reactions occuring all at once can cause the star to expand, pulsate, and even blow itself apart.