Abstract

Contributed Talk - Plenary

Fragmentation and accretion in massive star-forming cores

Nuray Ortaköse
Universität zu Köln

The field of massive star formation continues to be riddled with unanswered questions. Two main theories on accretion have been debated in recent years: Competitive Accretion and Core Accretion. In Core Accretion, a molecular cloud will fragment into cores with different masses. The high-mass stars are formed through the collapse of self-gravitating, dense cores. Thus, the final mass of the star is dependent on the core mass. In Competitive Accretion, the mass is accreted from a wider region of the clump, while never being in a phase of a gravitationally bound core. The clump feeds the central region where the forming stars compete for mass, and the most massive star forms at the bottom of the potential well. In our work, we investigate the accretion and fragmentation process from the simulation of a high-mass star-forming collapsing cloud, by using the tracer particle data to retrieve the history of the gas evolution. Initial conditions are a centrally peaked density profile and αvir < 1. The considered feedback processes are ionizing radiation and radiation pressure. We find that accretion happens episodically and gets partially suppressed for massive stars (> 8 M⊙). Furthermore, we find that the massive stars draw mass from a large mass reservoir, which exceeds the central region. This mass reservoir replenishes the central region, while the stars compete for the mass. Additionally, we see that massive stars also form outside the central region, showing that they are provided with their own mass reservoir, while also competing with the other stars. We also see that the mass follows free fall, so the velocity is dependent on the mass of the star, the distance between the star and the drawn mass, and the elapsed time. We conclude that the accretion process is most likely competitive.