A census of OB stars within 1 kpc

Finally, we have also exploited our list of OB stars to estimate their scale height (76+/-1pc), a local star formation rate of 2896^+417^_-1_M_{sun}_/Myr and a local core-collapse supernova rate of ~15-30 per Myr. We extrapolate these rates to the entire Milky Way to derive a Galactic SFR of 0.67^+0.09^_-0.01_M_{sun}_/yr and a core-collapse supernova rate of 0.4-0.5 per century. These are slightly lower than previous estimates, which we attribute to improvements in our census of OB stars and changes to evolutionary models.

We calculate a near-Earth core collapse supernova rate of ~2.5 per Gyr that supports the view that nearby supernova explosions could have caused one or more of the recorded mass extinction events on Earth.