On the formation of very metal-poor stars: The case of SDSS J1029151+172927

TL;DR

This paper investigates the formation mechanisms of extremely metal-poor stars, using the star SDSS J1029151+172927 to argue that dust cooling, rather than metal-line cooling, is the primary process influencing their formation and mass.

Contribution

The study provides evidence supporting dust cooling as the dominant mechanism in forming very metal-poor stars, challenging previous models based on metal-line cooling.

Findings

Dust cooling likely caused the formation of SDSS J1029151+172927

Dust-induced fragmentation influences the mass of extremely metal-poor stars

Metal-line cooling is less significant in the formation of such stars

Abstract

The formation of stars is a key process in the early universe with far reaching consequences for further cosmic evolution. While stars forming from truly primordial gas are thought to be considerably more massive than our Sun, stars in the universe today have typical masses below one solar mass. The physical origin of this transition and the conditions under which it occurs are highly debated. There are two competing models, one based on metal-line cooling as the primary agent and one based on dust cooling. The recent discovery of the extremely metal poor star SDSS J1029151+172927 provides a unique opportunity to distinguish between these two models. Based on simple thermodynamic considerations we argue that SDSS J1029151+172927 was more likely formed as a result of dust continuum cooling rather than cooling by metal lines. We conclude that the masses of extremely metal-poor stars are determined by dust-induced fragmentation.