Download Quiz Solution: 1 April 2013 What does it mean when an astronomer

Quiz Solution: 1 April 2013
What does it mean when an astronomer says that a star "moves" from one place to another on an H-R
Diagram? Can you provide an example of this?
As stars evolve and change structure, their radii and temperatures also change. Since a
star's luminosity is dependent on both temperature and radius, the luminosity also can
change as a star evolves. If we plot a single star in an H-R diagram at several different
stages of evolution we will find that it is located in different regions of the diagram. In this
way, we speak of a star "moving" in the H-R diagram because of structural changes as the
star evolves. The path that a star moves on in the H-R diagram is called an evolutionary
track.
Example: End of core hydrogen fusion and the ascent of the red giant branch (RGB)