Mittwoch, 12. Mai 2010 - 15:15
"The role of radiation pressure and accretion disks in the formation of massive stars"
Zusammenfassung. We investigate the radiation pressure problem in the formation of massive stars in 1, 2, and 3D radiation hydrodynamics simulations of collapsing pre-stellar cores. In contrast to previous research, we 1) consider frequency dependent radiation feedback, 2) resolve the dust condensation front in the vicinity of the forming star down to 1.27 AU, 3) compute the whole accretion phase of the star up to several 10^5 yr, and 4) perform a broad survey of the parameter space. Results:Our simulation series demonstrate the need of incorporating the dust condensation front to compute the radiation pressure feedback correctly. The most fundamental result is that the formation of a massive accretion disk in slowly rotating cores bypasses the radiative flux through the optically thin atmosphere. In this way, first, the radiation pressure onto the accretion flow is strongly diminished. Secondly, the launch of a stable radiation pressure driven outflow in the bi-polar direction decreases the star formation efficiency of the core. The self-gravity of the massive accretion disk drives a sufficiently high accretion rate to overcome the residual radiation pressure in the radial direction. For an initial pre-stellar core mass of 60, 120, 240, and 480 M_sol these mechanisms allow the star to grow up to 27, 57, 93, and more than 130 M_sol respectively.