The 9th Magnitude CEMP star BD+44°493: Origin of its Carbon Excess and Beryllium Abundance

We performed a chemical abundance analysis of the very bright (V = 9.1) carbon-enhanced metal-poor (CEMP) star BD+44°493, which is the first star found with metallicity [Fe/H] < —3.5 and an apparent magnitude V < 12. The star is classified as a CEMP-no" subgiant, and its abundance pattern implies that a first-generation faint supernova is the most likely origin of its carbon excess. We set an very low upper limit on this starʹs beryllium abundance, which demonstrates that high C and O abundances do not necessarily imply high Be abundances.