Which is used observationally to determine the age of a star cluster?

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The luminosity of the main sequence turn-off point is used observationally to determine the age of a star cluster. This is because as a star cluster ages, the more massive stars burn through their fuel faster and leave the main sequence earlier than less massive stars. Therefore, the luminosity of the main sequence turn-off point reveals the age of the cluster. The luminosity of the main sequence turn-off point is used observationally to determine the age of a star cluster. This is because a star cluster begins with a range of masses and as the stars evolve, they move off the main sequence at different rates. The position of the turn-off point on the Hertzsprung-Russell diagram corresponds to the mass ranges of the stars that are just leaving the main sequence, and thus the age of the cluster can be estimated from this point.

Which Is Used Observationally to Determine the Age of a Star