The graph that shows the relationship between a star's absolute magnitude and temperature is called a Hertzsprung-Russell diagram, or HR diagram for short.

Here's why:

* Absolute magnitude represents a star's intrinsic brightness, meaning how bright it would appear if it were at a standard distance from Earth.

* Temperature is a key factor in determining the color and spectral class of a star.

The HR diagram plots stars based on these two properties, revealing important patterns about their evolution and characteristics.

Let me know if you'd like more details about the HR diagram!