We investigate the origin of carbon-enhanced metal-poor ( CEMP ) stars starting from the recently discovered [ Fe / H ] < -7.1 star SMSS J031300 ( Keller et al .
2014 ) .
We show that the elemental abundances observed on the surface of SMSS J031300 can be well fit by the yields of faint , metal free , supernovae .
Using properly calibrated faint supernova explosion models , we study , for the first time , the formation of dust grains in such carbon-rich , iron-poor supernova ejecta .
Calculations are performed assuming both unmixed and uniformly mixed ejecta and taking into account the partial destruction by the supernova reverse shock .
We find that , due to the paucity of refractory elements beside carbon , amorphous carbon is the only grain species to form , with carbon condensation efficiencies that range between ( 0.15-0.84 ) , resulting in dust yields in the range ( 0.025-2.25 ) M _ { \odot } .
We follow the collapse and fragmentation of a star forming cloud enriched by the products of these faint supernova explosions and we explore the role played by fine structure line cooling and dust cooling .
We show that even if grain growth during the collapse has a minor effect of the dust-to-gas ratio , due to C depletion into CO molecules at an early stage of the collapse , the formation of CEMP low-mass stars , such as SMSS J031300 , could be triggered by dust cooling and fragmentation .
A comparison between model predictions and observations of a sample of C-normal and C-rich metal-poor stars supports the idea that a single common pathway may be responsible for the formation of the first low-mass stars .