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A G0 III star with a mass of about 1 M⊙ sits on the horizontal branch. Horizontal branch stars are in the helium-burning phase of stellar evolution. For this process,
3He→C +energy
If the star has a luminosity of 100 L⊙, estimate the size of this star assuming it has a temperature of 6000 K. What is the thermal time scale (time for the star to radiate away all its potential energy) if only 10% of the star’s mass is in the form of helium?
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