Lives of Low Mass Stars

The battle against the inexorable force of gravity ... lost. Part I.

Low mass stars: less than 2 solar masses. Convective zone + radiative core.
Intermediate: 2-8 solar masses. Radiative structure
High mass stars: more than 8 solar masses. Convective core + radiative mantle.

Where's the bottom of the main sequence?
0.076 solar masses.
Below this mass the core never gets hot enough to fuse H stably.
Why doesn't it collapse?
Degenerate pressure (see White Dwarfs below)