The Formation and Fragmentation of Disks around Primordial Protostars

TL;DR

This paper uses numerical simulations to demonstrate that the first stars in the universe often formed in tight multiple systems due to gravitational fragmentation of their accretion disks, challenging previous beliefs.

Contribution

It reveals that primordial star disks were prone to fragmentation, leading to the formation of close binary and multiple star systems, a novel insight into early cosmic star formation.

Findings

Primordial disks were gravitationally unstable and fragmented.

Formation of tight binary and multiple star systems was common.

First stars often formed in multiple systems, not solitary.

Abstract

The very first stars to form in the Universe heralded an end to the cosmic dark ages and introduced new physical processes that shaped early cosmic evolution. Until now, it was thought that these stars lived short, solitary lives, with only one extremely massive star, or possibly a very wide binary system, forming in each dark matter minihalo. Here we describe numerical simulations that show that these stars were, to the contrary, often members of tight multiple systems. Our results show that the disks that formed around the first young stars were unstable to gravitational fragmentation, possibly producing small binary and higher-order systems that had separations as small as the distance between the Earth and the Sun.