Multiple Choice
When does a protostar become a main-sequence star?
A) When the rate of hydrogen fusion becomes high enough to balance the rate at which the star radiates energy into space
B) When a piece of a molecular cloud first begins to contract into a star
C) When it becomes luminous enough to emit thermal radiation
D) At the instant that the first hydrogen fusion reactions occur in the protostar's core
Correct Answer:
Verified
Correct Answer:
Verified
Q34: Choose from the list below for the
Q40: Although some photographs show what looks like
Q65: Briefly describe how a star forms.
Q101: Explain how some stars form in binary
Q101: Which of the following statements about various
Q103: What star is the most likely to
Q104: Which of the following properties describes a
Q105: Most interstellar dust grains<br>A) were produced in
Q109: What does the CNO cycle and the
Q111: What happens after the helium flash?<br>A) The