The Formation of Massive Star Systems by Accretion

TL;DR

This study uses 3D radiation-hydrodynamic simulations to show that massive stars can continue to grow via accretion despite strong radiation pressure, due to instabilities that channel gas inward.

Contribution

It demonstrates that gravitational and Rayleigh-Taylor instabilities enable accretion onto massive stars, challenging previous assumptions about radiation pressure halting star growth.

Findings

Radiation pressure does not prevent accretion in massive star formation.

Instabilities create channels allowing gas to reach the star system.

Formation of small multiple systems through disk fragmentation.

Abstract

Massive stars produce so much light that the radiation pressure they exert on the gas and dust around them is stronger than their gravitational attraction, a condition that has long been expected to prevent them from growing by accretion. We present three-dimensional radiation-hydrodynamic simulations of the collapse of a massive prestellar core and find that radiation pressure does not halt accretion. Instead, gravitational and Rayleigh-Taylor instabilities channel gas onto the star system through non-axisymmetric disks and filaments that self-shield against radiation, while allowing radiation to escape through optically-thin bubbles. Gravitational instabilities cause the disk to fragment and form a massive companion to the primary star. Radiation pressure does not limit stellar masses, but the instabilities that allow accretion to continue lead to small multiple systems.