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(please type not write down the answer) astronomy 3. A main sequence star of mass 15...

(please type not write down the answer) astronomy

3. A main sequence star of mass 15 M⊙ has a luminosity of approximately 10,000 L⊙ . a. At what rate does mass vanish as H is fused to He in the star’s core? Note: When we say “mass vanish” what we really mean is “gets converted into energy and leaves the star as light”. b. At what rate is H converted into He? To do this you need to take into account that for every kg of hydrogen burned, only 0.7% gets converted into energy while the rest turns into helium. c. Assuming that only the 10% of the star’s mass in the central regions will get hot enough for fusion, calculate the main sequence lifetime of the star. Put your answer in years, and compare to the lifetime of the Sun. It should be much, much shorter.

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