We present detailed chemical abundances for the bright carbon-enhanced metal-poor ( CEMP ) star BD+44 ^ { \circ } 493 , previously reported on by Ito et al .
Our measurements confirm that BD+44 ^ { \circ } 493 is an extremely metal-poor ( [ Fe/H ] = -3.8 ) subgiant star with excesses of carbon and oxygen .
No significant excesses are found for nitrogen and neutron-capture elements ( the latter of which place it in the CEMP-no class of stars ) .
Other elements that we measure exhibit abundance patterns that are typical for non-CEMP extremely metal-poor stars .
No evidence for variations of radial velocity have been found for this star .
These results strongly suggest that the carbon enhancement in BD+44 ^ { \circ } 493 is unlikely to have been produced by a companion asymptotic giant-branch star and transferred to the presently observed star , nor by pollution of its natal molecular cloud by rapidly-rotating , massive , mega metal-poor ( [ Fe/H ] < -6.0 ) stars .
A more likely possibility is that this star formed from gas polluted by the elements produced in a “ faint ” supernova , which underwent mixing and fallback , and only ejected small amounts of elements of metals beyond the lighter elements .
The Li abundance of BD+44 ^ { \circ } 493 ( A ( Li ) = \log ( Li/H ) +12 = 1.0 ) is lower than the Spite plateau value , as found in other metal-poor subgiants .
The upper limit on Be abundance ( A ( Be ) = \log ( Be/H ) +12 < -1.8 ) is as low as those found for stars with similarly extremely-low metallicity , indicating that the progenitors of carbon- ( and oxygen- ) enhanced stars are not significant sources of Be , or that Be is depleted in metal-poor subgiants with effective temperatures of \sim 5400 K .