High-Entropy Polar Regions Around the First Protostars

TL;DR

This paper uses simulations to identify hot atomic gas regions around the first protostars, highlighting their potential role in influencing star formation and the importance of multi-dimensional modeling.

Contribution

It introduces the concept of high-entropy polar regions in primordial star formation and emphasizes their significance in accretion dynamics.

Findings

Hot atomic gas regions exist at high densities and temperatures.

These regions may regulate accretion by clearing polar areas.

Multi-dimensional effects are crucial for accurate star formation models.

Abstract

We report on simulations of the formation of the first stars in the Universe, where we identify regions of hot atomic gas (fH2 < 10-6) at densities above 10-14 g/cc, heated to temperatures ranging between 3000 and 8000 K. Within this temperature range atomic hydrogen is unable to cool effectively. We describe the kinetic and thermal characteristics of these regions and investigate their origin. We find that these regions, while small in total mass fraction of the cloud, may be dynamically important over the accretion timescale for the central clump in the cloud, particularly as a chemical, rather than radiative, mechanism for clearing the polar regions of the accretion disk of material and terminating accretion along these directions. These inherently three-dimensional effects stress the need for multi-dimensional calculations of protostellar accretion for reliable predictions of the masses of the very first stars.