New Estimates of the Solar-Neighborhood Massive Star Birthrate and the Galactic Supernova Rate

The birthrate of stars of masses ⩾10 M ⊙ is estimated from a sample of just over 400 O3–B2 dwarfs within 1.5 kpc of the Sun and the result extrapolated to estimate the Galactic supernova rate contributed by such stars. The solar-neighborhood Galactic-plane massive star birthrate is estimated at ∼176 stars kpc -3 Myr -1 . On the basis of a model in which the Galactic stellar density distribution comprises a "disk+central hole" like that of the dust infrared emission (as proposed by Drimmel and Spergel), the Galactic supernova rate is estimated at probably not less than ∼1 nor more than ∼2 per century and the number of O3–B2 dwarfs within the solar circle at ∼200,000.