We analyze a high-resolution , high signal-to-noise spectrum of the carbon-rich , extremely metal-poor star CS 29498–043 , obtained with the Subaru Telescope High Dispersion Spectrograph .
We find its iron abundance is extremely low ( [ Fe/H ] = -3.7 ) , placing it among the few stars known with [ Fe/H ] \leq - 3.5 , while Mg and Si are significantly overabundant ( [ Mg/Fe ] = +1.8 , and [ Si/Fe ] = +1.1 ) compared with stars of similar metallicity without carbon excess .
Overabundances of N and Al were also found .
These characteristics are similar to the carbon-rich , extremely metal-poor star CS 22949–037 .
Though the sample is small , our discovery of CS 29498–043 suggests the existence of a class of extremely metal-poor stars with large excesses of C , N , Mg , and Si .