The role of accretion disks in the formation of massive stars

TL;DR

This study uses advanced radiation hydrodynamics simulations to explore how accretion disks influence the formation of massive stars, emphasizing the importance of dust sublimation fronts and anisotropic radiation fields in enabling high-mass star growth.

Contribution

It provides the first comprehensive 2D simulation of the entire accretion phase of massive star formation, highlighting the role of dust sublimation and radiation anisotropy.

Findings

High-mass stars up to 137 solar masses can form via accretion disks.

Dust sublimation fronts are crucial for effective shielding and sustained accretion.

Bipolar outflows are stable and grow over time, consistent with observations.

Abstract

We present radiation hydrodynamics simulations of the collapse of massive pre-stellar cores. We treat frequency dependent radiative feedback from stellar evolution and accretion luminosity at a numerical resolution down to 1.27 AU. In the 2D approximation of axially symmetric simulations, it is possible for the first time to simulate the whole accretion phase of several 10^5 yr for the forming massive star and to perform a comprehensive scan of the parameter space. Our simulation series show evidently the necessity to incorporate the dust sublimation front to preserve the high shielding property of massive accretion disks. Our disk accretion models show a persistent high anisotropy of the corresponding thermal radiation field, yielding to the growth of the highest-mass stars ever formed in multi-dimensional radiation hydrodynamics simulations. Non-axially symmetric effects are not necessary to sustain accretion. The radiation pressure launches a stable bipolar outflow, which grows in angle with time as presumed from observations. For an initial mass of the pre-stellar host core of 60, 120, 240, and 480 Msol the masses of the final stars formed in our simulations add up to 28.2, 56.5, 92.6, and at least 137.2 Msol respectively.