The unexpectedly large proportion of high-mass starforming cores in a Galactic mini-starburst

Abstract

Understanding the processes that determine the stellar Initial Mass Function (IMF) is a critical unsolved problem, with profound implications for many areas of astrophysics1. In molecular clouds, stars are formed in cores, gas condensations which are suffciently dense that gravitational collapse converts a large fraction of their mass into a star or small clutch of stars. In nearby star-formation regions, the core mass function (CMF) is strikingly similar to the IMF, suggesting that the shape of the IMF may simply be inherited from the CMF2–5. Here we present 1:3mm observations, obtained with ALMA, the world’s largest interferometer, of the active star-formation region W43-MM1, which may be more representative of the Galactic-disk regions where most stars form6, 7 . The unprecedented resolution of these observations reveals, for the first time, a statistically robust CMF at high masses, with a slope that is markedly shallower than the IMF. This seriously challenges our understanding of the origin of the IMF.