Multiple Choice
What causes the core of a star to contract during the main-sequence phase of the star's life?
A) The conversion of hydrogen into helium reduces the number of particles in the core.
B) Convection in the outer layers carries energy out of the core more efficiently as the star ages.
C) Helium has a larger atomic weight than hydrogen and exerts a stronger gravitational pull on the core.
D) The rate of core hydrogen burning decreases as the hydrogen is used up, reducing the rate of energy generation.
Correct Answer:

Verified
Correct Answer:
Verified
Q45: If you examine many main-sequence stars, the
Q46: RR Lyrae variables are likely to be
Q47: What is the minimum mass necessary in
Q48: When a Cepheid variable star reaches maximum
Q49: Suppose that, when the stars in a
Q51: If you were to look at 1
Q52: In some binary star systems, such
Q53: The Kelvin-Helmholtz contraction supplies significant energy to
Q54: Where on the H-R diagram would you
Q55: For a main-sequence star of less than