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Globular clusters are among the
oldest objects in the galaxy. Globular Clusters are made
up of hundreds of thousands of stars and are densely packed
at their centers.
Because these clusters are so old, the most massive stars in these clusters are less massive than our Sun! All stars more massive than this have run out of fuel and died long ago.
If stars the mass of the Sun have died, what is the minimum AGE of this cluster? |
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Looking at real data from a globular cluster
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To the left is a real H-R diagram for a globular
cluster called M13. Can you find the Main Sequence
in this H-R Diagram?
Can you find the tip of the Red Giant Phase?
Can you guess where in the diagram the Helium flash occurs?
Can you tell where Helium fusion is likely occurring?
What would you estimate to be the age of this cluster? |
It should be clear from the examples above, with the use of an HR diagram, we can tell a lot about a clusters properties, like age. But most important, it gives us insight into the evolution of stars, something we'll never live long enough to see directly.