We present a 1D LTE chemical abundance analysis of the very bright ( V = 9.1 ) Carbon-Enhanced Metal-Poor ( CEMP ) star ( catalog BD $ +44^ ∘ 493 $ ) , based on high-resolution , high signal-to-noise spectra obtained with Subaru/HDS .
The star is shown to be a subgiant with an extremely low iron abundance ( [ Fe/H ] = -3.7 ) , while it is rich in C ( [ C/Fe ] = +1.3 ) and O ( [ O/Fe ] = +1.6 ) .
Although astronomers have been searching for extremely metal-poor stars for decades , this is the first star found with [ Fe/H ] < -3.5 and an apparent magnitude V < 12 .
Based on its low abundances of neutron-capture elements ( e.g. , [ Ba/Fe ] = -0.59 ) , ( catalog BD $ +44^ ∘ 493 $ ) is classified as a ” CEMP-no ” star .
Its abundance pattern implies that a first-generation faint supernova is the most likely origin of its carbon excess , while scenarios related to mass loss from rapidly-rotating massive stars or mass transfer from an AGB companion star are not favored .
From a high-quality spectrum in the near-UV region , we set an very low upper limit on this star ’ s beryllium abundance ( A ( { Be } ) = \log ( { Be / H } ) +12 < -2.0 ) , which indicates that the decreasing trend of Be abundances with lower [ Fe/H ] still holds at [ Fe/H ] < -3.5 .
This is the first attempt to measure a Be abundance for a CEMP star , and demonstrates that high C and O abundances do not necessarily imply high Be abundances .