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