What prevents a brown dwarf from undergoing nuclear fusion?
A)Degeneracy pressure halts the contraction of a protostar so the core never becomes hot or dense enough for nuclear fusion.
B)There is not enough mass to maintain nuclear reactions in a self-sustaining way.
C)The surface temperature never rises high enough for the radiation to be trapped and heat their interior to the temperatures required for nuclear fusion.
D)Radiation pressure halts the contraction of a protostar so the core never becomes hot or dense enough for nuclear fusion.
E)There are too many heavy elements and not enough hydrogen for fusion to occur in a self-sustaining way.

Question

Quizplus · Accepted Answer

Brown dwarfs are failed stars that do not have enough mass to undergo sustained nuclear fusion, but they have enough mass to collapse under gravity and heat up. However, degeneracy pressure halts the contraction of a protostar so the core never becomes hot or dense enough for nuclear fusion. Degeneracy pressure is the result of the Pauli exclusion principle, which states that no two fermions (such as electrons) can occupy the same state simultaneously. This creates a pressure that opposes gravity and prevents further contraction of the brown dwarf's core.

What Prevents a Brown Dwarf from Undergoing Nuclear Fusion