Briefly Explain Why There Is a Main Sequence on the H-R

Q5: Define nuclear fusion.

Q6: If you observe a variable star with

Q7: Giant and supergiant stars are rare because

Q8: When the Sun moves off the main

Q9: Explain how one of the four laws

Q11: Astronomers determine the internal structure of a

Q12: When a gas is so dense that

Q13: The period-luminosity relation for Cepheid and RR

Q14: Observing star clusters will give astronomers needed

Q15: List the two basic types of intrinsic