CIRCUMVENTING THE RADIATION PRESSURE BARRIER IN THE FORMATION OF MASSIVE STARS VIA DISK ACCRETION

Abstract

We present radiation hydrodynamics simulations of the collapse of massive\npre-stellar cores. We treat frequency dependent radiative feedback from stellar\nevolution and accretion luminosity at a numerical resolution down to 1.27 AU.\nIn the 2D approximation of axially symmetric simulations, it is possible for\nthe first time to simulate the whole accretion phase (up to the end of the\naccretion disk epoch) for the forming massive star and to perform a broad scan\nof the parameter space. Our simulation series show evidently the necessity to\nincorporate the dust sublimation front to preserve the high shielding property\nof massive accretion disks. While confirming the upper mass limit of\nspherically symmetric accretion, our disk accretion models show a persistent\nhigh anisotropy of the corresponding thermal radiation field. This yields to\nthe growth of the highest-mass stars ever formed in multi-dimensional radiation\nhydrodynamics simulations, far beyond the upper mass limit of spherical\naccretion. Non-axially symmetric effects are not necessary to sustain\naccretion. The radiation pressure launches a stable bipolar outflow, which\ngrows in angle with time as presumed from observations. For an initial mass of\nthe pre-stellar host core of 60, 120, 240, and 480 Msun the masses of the final\nstars formed in our simulations add up to 28.2, 56.5, 92.6, and at least 137.2\nMsun respectively.\n