When Does a Protostar Become a Main-Sequence Star

question 84

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

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A financial ratio that indicates the percentage of revenue that exceeds the costs associated with making and selling products or providing services.

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