Now we get to some real meat of astrophysics. We discuss the relationship between mass, luminosity, and lifespan of main sequence stars. It is an amazing discovery that mass is known to be tightly correlated to luminosity for Main Sequence stars. Also, the luminosity is tightly related to spectral type. So, just get the spectrum, and you know the mass! This is part of my complete intro Astronomy class that I taught at Willam Paterson University and CUNY Hunter.

Hertzsprung-Russell diagram: https://en.wikipedia.org/wiki/Hertzsp...
Luminosity/Radius/Temperature Relation: https://en.wikipedia.org/wiki/Luminos...
Stellar Evolution: https://en.wikipedia.org/wiki/Stellar...
Stellar Lifetime: http://hyperphysics.phy-astr.gsu.edu/...
Main-Sequence Effective Temperatures from a Revised Mass-Luminosity Relation Based on Accurate Properties: https://arxiv.org/pdf/1501.06585.pdf
CNO Cycle: https://en.wikipedia.org/wiki/CNO_cycle
Proton-Proton Chain: https://en.wikipedia.org/wiki/Proton-...