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We present an elemental-abundance analysis, in the near-ultraviolet (NUV)spectral range, for the extremely metal-poor star BD+44 493, a 9th magnitudesub-giant with [Fe/H] = -3.8 and enhanced carbon, based on data acquired withthe Space Telescope Imaging Spectrograph on the Hubble Space Telescope. Thisstar is the brightest example of a class of objects that, unlike the greatmajority of carbon-enhanced metal-poor (CEMP) stars, does not exhibitover-abundances of heavy neutron-capture elements (CEMP-no). In this paper, wevalidate the abundance determinations for a number of species that werepreviously studied in the optical region, and obtain strong upper limits forberyllium and boron, as well as for neutron-capture elements from zirconium toplatinum, many of which are not accessible from ground-based spectra. The boronupper limit we obtain for BD+44 493, logeps(B) < -0.70, the first suchmeasurement for a CEMP star, is the lowest yet found for very and extremelymetal-poor stars. In addition, we obtain even lower upper limits on theabundances of beryllium, logeps(Be) < -2.3, and lead, logeps(Pb) < -0.23([Pb/Fe] < +1.90), than those reported by previous analyses in the opticalrange. Taken together with the previously measured low abundance of lithium,the very low upper limits on Be and B suggest that BD+44 493 was formed at avery 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-processproduction of the heavy-element abundance patterns in CEMP-no stars.

Hubble Space Telescope Near-Ultraviolet Spectroscopy of the Bright CEMP-no Star BD+44 493