Stars are characterized by their mass. They range from about a thousandth the mass of the sun (where they merge into “brown dwarfs and gas giant planets), to about a 100 solar masses (beyond that they are unstable). The number of stars of each mass decreases rapidly as you sample higher masses, i.e.,small stars are much more common than large stars, and there is no quantum break in that “mass function”.

Stellar size, luminosity and temperature also vary enormously, and are not constant throughout the life of a star. Stars evolve. As they evolve they move around the Hertzprung-Russel diagram, spending a long time in some areas, and scooting through other parts of it relatively quickly. Most stars spend most of their lives on the main sequence, a curve that arcs from the upper left to lower right of the diagram, and where the star’s position depends on the mass it had when it started.

Our sun started off as a blue giant, quickly stabilized as a yellow, main sequence subdwarf where it will spend most of its life, and briefly swell up to become a red giant, before eventually shrinking to become a red dwarf. The amount of time it spends in each stage depends pretty much on the mass it had when it started. The more massive a star is, the brighter it burns, and the less time it lasts before it dies. A minority of stars, (above a certain mass, called Chandrasekhar’s Limit, roughly two solar masses), eventually become unstable and go supernova, the remnant becoming a white dwarf, neutron star, or black hole depending on how massive it was when it blew.

Stars like our sun die more quietly, winding up as red dwarfs, and eventually black dwarfs: black, burned out cinders. This final red dwarf stage lasts so long that the universe isn’t old enough for any black dwarfs to be around yet.

All of this was figured out in the last half of the twentieth century.

I would imagine gravity would simply suck up whatever was in the local area until it lit off, but somehow homogenity went to hell and there are all different kinds. But I wonder if there is a linear uniformity in the different kinds or if some sizes and temperatures are preferred over others.