What two fundamental physical characteristics are mapped against each other on the H-R diagram?

Answer

Luminosity and Surface Temperature

The H-R diagram is fundamentally a scatter plot mapping a star's intrinsic brightness (luminosity or absolute magnitude) against its surface temperature (or spectral class).

What two fundamental physical characteristics are mapped against each other on the H-R diagram?

#Videos

HR Diagram Explained - Star Color, Temperature and Luminosity

temperaturesequencestarLuminositydiagram