A Keck HIRES Investigation of the Metal Abundances and Kinematics of Three Damped Lyα Systems toward Q2206-199

We present high-resolution, high signal-to-noise ratio spectra of the QSO Q2206-199 obtained with HIRES on the 10 m W. M. Keck Telescope. Our analysis focuses on the two previously identified damped Ly? systems found at z = 1.920 and z = 2.076. For the z = 1.920 system, we measure accurate abundances (relative to solar) for Fe, Cr Si, Ni, Ti, and Zn: [Fe/H] = -0.705 ? 0.097, [Cr/H] = -0.580 ? 0.100, [Si/H] = -0.402 ? 0.098, [Ni/H] = -1.012 ? 0.095, [Ti/H] = -0.776 ? 0.081, and [Zn/H] = -0.379 ? 0.097. This system exhibits the highest metallicity we have measured for a damped Ly? system. By contrast the z = 2.076 system is the most metal poor ([Zn/H] 19.0 assuming metallicity relative to solar equal to 0 and no depletion. Together with the damped system at z = 1.920, this marks the first confident (>5 ?) detection of Ti in QSO absorption-line systems. We analyze the abundance ratios [Mn/Fe] and [Ti/Fe] and their values are inconsistent with significant dust depletion, yet consistent with the abundance pattern detected for halo stars in the Galaxy (Lu, Sargent, & Barlow 1996). Finally, we identify a C IV system at z = 2.014 that shows a very narrow feature in Si IV and C IV absorption. The corresponding b-values (5.5 and 8.9 km s-1 for Si IV and C IV, respectively) for this component suggest a temperature of 4.7 ? 104 K. Because collisional ionization can explain the observed abundances only for T > 8 ? 104 K, we contend these ions must have formed through a different physical process (e.g., photoionization).

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