The formation of the primitive star SDSS J102915+172927: does the grain distribution matter?
Understanding how the extremely metal poor star SDSS J102915+172927 was formed is of fundamental importance to probe the chemical and physical conditions of primordial stars, and contributes to improve our knowledge on the transition between the first and the second generation of stars in the Universe. In this Letter, we perform three dimensional cosmological hydrodynamical high resolution simulations of dust enriched halos during the early stages of the collapse process including an accurate treatment of the dust physics. We employ the astrochemistry package KROME coupled with the hydrodynamical code ENZO assuming grain size distributions produced by the explosion of core collapse supernovae of 20 and 35 M$_\odot$ primordial stars exposed to reverse shocks, which are suitable to reproduce the chemical pattern of the SDSS J102915+172927 star. We compare these simulations to runs with a grain composition typical for the Milky Way. We find that the total dust mass from Population III supernovae is the most important factor which drives the thermal evolution and the dynamical properties of the halos, and that the composition, the dust optical properties, and the size range have only minor effects on the results.