What is the life expectancy of a 16-solar-mass star?

Answer 1

A 16.0 solar mass star would spend about 11.7 million years on the main sequence (depending on the metallicity). After approximately 13.0 million years it would become a 1.5 solar mass (approx.) neutron star. This was calculated using metallicity z=0.02 (solar)

Answer 2

No more than a few million years.

Stars are kind of weird when it comes to their fuel source. Fusion only occurs in the core of the star where the temperature and pressures get high enough to smash the atoms together all the way through to Iron. There is also a process of convection occurring in the insides of stars. Just like with convection currents in the Earth's mantle, these currents help mix the hydrogen in the star. Smaller stars may be fully convective. They could take TRILLIONS of years to exhaust all of their hydrogen fuel.

The larger stars only have convection going on in a relatively small shell around the core. When these stars go supernova a good portion of the star is still hydrogen!

Another thing that these larger stars have going against them is their sheer gravity. Gravity want's to crush down the star. To counteract the titanic force of gravity the core is furiously burning it's fuel to create an outward pressure to prevent core collapse.

Pretty nifty stuff eh?