Beryllium and Alpha-Elements in Metal-Poor Stars

Ann Merchant Boesgaard
University of Hawaii, Manoa

ABSTRACT

We have obtained Keck HIRES spectra of over 100 stars with [Fe/H] = -0.5 to -3.5 to determine Be abundances. We have found the stellar parameters spectroscopically from line measurements of Fe I, Fe II and Ti I, Ti II. Spectrum synthesis techniques have been use to find Be from the Be II resonance doublet and to find O from the electronic transitions of OH in the ultraviolet spectral region. In addition to abundances for Be, O, Ti and Fe, we have found the Mg abundance from 1-3 lines of Mg I. A(Be) = log (Be/H) + 12 increases with increasing [Fe/H], [O/H], [Mg/H], and [Ti/H], all with slopes near 1.0, although a change in slope near [O/H] = -1.3 provides a better fit to the data. The correlations between [Fe/H] and each of [O/H], [Mg/H], and [Ti/H] are remarkably tight over three orders of magnitude in [Fe/H]. We have examined whether there are differences in the Galactic evolution of Be in dissipative, accretive, and retrograde populations of stars.