Massive Star Formation via High Accretion Rates and Early Disk‐driven Outflows

We present an investigation of massive star formation that results from thegravitational collapse of massive, magnetized molecular cloud cores. Weinvestigate this by means of highly resolved, numerical simulations of initialmagnetized Bonnor-Ebert-Spheres that undergo collapse and cooling. By comparingthree different cases - an isothermal collapse, a collapse with radiativecooling, and a magnetized collapse - we show that massive stars assemblequickly with mass accretion rates exceeding 10^-3 Msol/yr. We confirm that themass accretion during the collapsing phase is much more efficient thanpredicted by selfsimilar collapse solutions, i.e. dM/dt ~ c^3/G. We find thatduring protostellar assembly the mass accretion reaches 20 - 100 c^3/G.Furthermore, we determined the self-consistent structure of bipolar outflowsthat are produced in our three dimensional magnetized collapse simulations.These outflows produce cavities out of which radiation pressure can bereleased, thereby reducing the limitations on the final mass of massive starsformed by gravitational collapse. Moreover, we argue that the extraction ofangular momentum by disk-threaded magnetic fields and/or by the appearance ofbars with spiral arms significantly enhance the mass accretion rate, therebyhelping the massive protostar to assemble more quickly.