If the Milky Way formed stars at approximately a constant rate over the last 14 billion years, what fraction of the M-type stars that ever formed in it can still be found as main-sequence stars today? (Note that M-type stars have a mass of approximately 0.5 M_SUN.) A) 10 percent B) 33 percent C) 50 percent D) 75 percent E) 100 percent

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Quizplus · Accepted Answer

M-type stars have very long lifespans, often exceeding the current age of the universe. Therefore, nearly all M-type stars that have ever formed are still on the main sequence today.

If the Milky Way Formed Stars at Approximately a Constant