A detailed elemental abundance analysis has been carried out for the very metal-poor ( [ Fe/H ] = -2.7 ) star BSÂ 16934–002 , which was identified in our previous work as a star exhibiting large overabundances of Mg and Sc .
A comparison of the abundance pattern of this star with that of the well-studied metal-poor star HDÂ 122563 indicates excesses of O , Na , Mg , Al , and Sc in BSÂ 16934–002 .
Of particular interest , no excess of C or N is found in this object , in contrast to CSÂ 22949–037 and CSÂ 29498–043 , two previously known carbon-rich , extremely metal-poor stars with excesses of the \alpha elements .
No established nucleosynthesis model exists that explains the observed abundance pattern of BSÂ 16934–002 .
A supernova model , including mixing and fallback , assuming severe mass loss before explosion , is discussed as a candidate progenitor of BSÂ 16934–002 .