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1.Explain the zero-age main sequence 2.Describe what happens to main-sequence st

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Question

1.Explain the zero-age main sequence 2.Describe what happens to main-sequence stars of various masses as they exhaust their hydrogen supply 3.Explain how star clusters help us understand the stages of stellar evolution 4.List the different types of star clusters and describe how they differ in number of stars, structure, and age 5.Explain why the chemical composition of globular clusters is different from that of open clusters 6.Explain how the H–R diagram of a star cluster can be related to the cluster’s age and the stages of evolution of its stellar members 7.Describe how the main-sequence turnoff of a cluster reveals its age 8.Explain what happens in a star’s core when all of the hydrogen has been used up 9.Define “planetary nebulae” and discuss their origin 10.Explain how and why massive stars evolve much more rapidly than lower-mass stars like our Sun

1.Explain the zero-age main sequence 2.Describe what happens to main-sequence stars of various masses as they exhaust their hydrogen supply 3.Explain how star clusters help us understand the stages of stellar evolution 4.List the different types of star clusters and describe how they differ in number of stars, structure, and age 5.Explain why the chemical composition of globular clusters is different from that of open clusters 6.Explain how the H–R diagram of a star cluster can be related to the cluster’s age and the stages of evolution of its stellar members 7.Describe how the main-sequence turnoff of a cluster reveals its age 8.Explain what happens in a star’s core when all of the hydrogen has been used up 9.Define “planetary nebulae” and discuss their origin 10.Explain how and why massive stars evolve much more rapidly than lower-mass stars like our Sun

1.Explain the zero-age main sequence 2.Describe what happens to main-sequence stars of various masses as they exhaust their hydrogen supply 3.Explain how star clusters help us understand the stages of stellar evolution 4.List the different types of star clusters and describe how they differ in number of stars, structure, and age 5.Explain why the chemical composition of globular clusters is different from that of open clusters 6.Explain how the H–R diagram of a star cluster can be related to the cluster’s age and the stages of evolution of its stellar members 7.Describe how the main-sequence turnoff of a cluster reveals its age 8.Explain what happens in a star’s core when all of the hydrogen has been used up 9.Define “planetary nebulae” and discuss their origin 10.Explain how and why massive stars evolve much more rapidly than lower-mass stars like our Sun

Explanation / Answer

SOLUTION:-

Every main sequence star was a zero age main sequence. when it first started fusing hydrogen into helium. It will stay thereafter on the main sequence until it can't burn hydrogen into helium in its core anymore, at which time it will be at "terminal age main sequence". the position of this sequence is  slightly to the left boundary of the main-sequence, but more broadly and generally towards the middle.