The surface of a protostar radiates energy while its core
A)shrinks and cools.
B)shrinks and maintains a constant temperature.
C)shrinks and heats.
D)expands and cools.

Question

Quizplus · Accepted Answer

As a protostar forms, gravity causes the core to shrink and heat up, eventually reaching temperatures at which fusion can begin. However, the outer layers of the protostar are still cool and opaque, preventing energy from escaping. As a result, the core continues to shrink and heat up until the temperature is high enough for radiation to escape from the surface. Therefore, as the surface radiates energy, the core continues to shrink and heat up, leading to a choice of C.

The Surface of a Protostar Radiates Energy While Its Core