The Most Important Factor Affecting a Star's Main-Sequence Lifetime Is

Q12: The sequence of reactions by which stars

Q13: The fusion of iron nuclei does not

Q14: An evolutionary track describes the career of

Q15: The least massive stars in which nuclear

Q16: If M is the mass of a

Q18: Which of the following is a key

Q19: Massive stars on the upper end of

Q20: What element is produced by the triple-alpha

Q21: The age of a cluster can be

Q22: Cluster A has no stars of spectral