1. The problem statement, all variables and given/known data A B0 star has a luminosity of ~ 16000 L(solar) and a mass of ~ 16 M(solar). Can you estimate the time on the main sequence for this star simply from considering the rest mass energy of the core of the star (~10% of the total, and fusion burns with an efficiency of about 0.7%) and its luminosity? 2. Relevant equations I know that for main sequence stars, L is proportional to M^3 3. The attempt at a solution I have no idea where to go with this question, i've trawled through so many webpages and textbooks without success. Any ideas?