The following questions refer to the H-R diagram below that shows the life track of a 1-solar-mass star,with various stages labeled with Roman numerals.

-During which stage is the star's energy supplied by gravitational contraction?
A)ii
B)iii
C)v
D)vi
E)viii

Question

The following questions refer to the H-R diagram below that shows the life track of a 1-solar-mass star,with various stages labeled with Roman numerals.
 
-During which stage is the star's energy supplied by gravitational contraction?
A)ii 
B)iii 
C)v 
D)vi 
E)viii

Quizplus · Accepted Answer

During stage ii, the star is a protostar and is not yet undergoing nuclear fusion. Its energy is supplied by gravitational contraction, as it continues to contract and heat up until the conditions for fusion are met.

The Following Questions Refer to the H-R Diagram Below That