Caption: A Hertzsprung-Russell (HR) diagram showing a representative sample post-main-sequence evolutionary tracks for single stars of various initial stellar masses, all with initial fiducial solar metallicity Z=0.02 and zero angular momentum.

Note the following HR diagram bands:

1. AGS = asymptotic giant branch.
2. BSG = blue supergiants.
3. LBV = luminous blue variable.
4. MS = main sequence.
5. RC = red clump: The stars in this HR diagram band are cool horizontal branch stars.
6. RG = red giant.
7. RSG = red supergiants.
8. SubG = subgiants.
9. WR = Wolf-Rayet star.
10. YSG = yellow supergiant.

The evolutionary tracks leave the main sequence mostly moving toward the upper right half of the HR diagram.

So post-main-sequence stars are typically cooler and, except at the high-mass end, brighter than than main-sequence stars.

In understanding stellar evolution, you should always remember the main-sequence rule (local link / general link: star_main_sequence_rule.html).

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