We present an elemental-abundance analysis , in the near-ultraviolet ( NUV ) spectral range , for the extremely metal-poor star ( catalog BD+44 $ ^ ∘ $ 493 ) , a 9th magnitude subgiant with [ Fe/H ] = -3.8 and enhanced carbon , based on data acquired with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope .
This star is the brightest example of a class of objects that , unlike the great majority of carbon-enhanced metal-poor ( CEMP ) stars , does not exhibit over-abundances of heavy neutron-capture elements ( CEMP-no ) .
In this paper , we validate the abundance determinations for a number of species that were previously studied in the optical region , and obtain strong upper limits for beryllium and boron , as well as for neutron-capture elements from zirconium to platinum , many of which are not accessible from ground-based spectra .
The boron upper limit we obtain for ( catalog BD+44 $ ^ ∘ $ 493 ) , log \epsilon ( B ) < -0.70 , the first such measurement for a CEMP star , is the lowest yet found for very and extremely metal-poor stars .
In addition , we obtain even lower upper limits on the abundances of beryllium , log \epsilon ( Be ) < -2.3 , and lead , log \epsilon ( Pb ) < -0.23 ( [ Pb/Fe ] < +1.90 ) , than those reported by previous analyses in the optical range .
Taken together with the previously measured low abundance of lithium , the very low upper limits on Be and B suggest that ( catalog BD+44 $ ^ ∘ $ 493 ) was formed at a very early time , and that it could well be a bona-fide second-generation star .
Finally , the Pb upper limit strengthens the argument for non- s -process production of the heavy-element abundance patterns in CEMP-no stars .