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Keck Hires Spectroscopy Of M92 Subgiants: Surprising Abundances Near The Turnoff, Jeremy R. King, Alex Stephens, Ann Merchant Boesgaard, Constantine P. Deliyannis
Keck Hires Spectroscopy Of M92 Subgiants: Surprising Abundances Near The Turnoff, Jeremy R. King, Alex Stephens, Ann Merchant Boesgaard, Constantine P. Deliyannis
Publications
Using high-resolution, moderate signal-to-noise ratio spectroscopy obtained with the 10 m Keck I Telescope and efficient HIRES echelle spectrograph, we derive abundances of several elements in subgiants near the M92 turnoff. As a consistency check, we also analyze the metal-poor field star HD 140283 and find an Fe abundance in fine agreement with many previous determinations. However, our M92 value ([Fe/H] = -2.52) is a factor of 2 lower than the abundance derived from its red giant members. Differences in model atmospheres, gf-values, and instrumental effects might account for this difference, but whether they in fact do so is unclear. …
Primordial Lithium: Keck Observations In M92 Turnoff Stars, Ann Merchant Boesgaard, Constantine Deliyannis, Alex Stephens, Jeremy R. King
Primordial Lithium: Keck Observations In M92 Turnoff Stars, Ann Merchant Boesgaard, Constantine Deliyannis, Alex Stephens, Jeremy R. King
Publications
We present new Keck I/HIRES observations at R\45,000 (\3 pixels) of seven stars near the turno† of the old, metal-poor globular cluster M92. In three of these stars, we have signal-to-noise ratios (S/Ns) of 40 pixel~1, and in the other four, the S/N is near 20. The Li abundance in star 18 is high compared with the halo Ðeld-star plateau and is similar to that in the remarkable Li-rich halo Ðeld star BD ]23¡3912. In addition to the high Li abundance in star 18, there is a dispersion in Li abundance in our seven stars covering the full range of …