Astronomers identify the "birth" of a real star (as opposed to the activities of a protostar) with what activity in the star?

Question

Quizplus · Accepted Answer

The "birth" of a real star is identified with the onset of nuclear fusion reactions inside its core, which marks the point at which the star becomes self-sustaining and begins to shine with its own light. Option A is incorrect because this describes the formation of a protostar, which is not yet a true star. Option B is incorrect because a star can still be embedded within its dust cloud and be visible. Option C is incorrect because a wind can be observed from both protostars and mature stars. Option E is incorrect because many objects emit infrared radiation, not just stars.

Astronomers Identify the "Birth" of a Real Star (As Opposed