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Session 84 - IGM.
Display session, Friday, January 09
One difficulty in the investigations of damped Lyman alpha (DLA) systems is that they occur in distant systems whose stellar and gaseous components are difficult to study. Nearby galaxies often have well-studied stellar and gaseous components, and here we report on absorption line observations caused by the S0 galaxy NGC 4203 (v_helio = 1086 km/s) against the background quasar Ton 1480 (z = 0.614; V = 16.5). Ton 1480 is projected 1.9' from the center of NGC 4203 (12 kpc for H_o = 50 km/s/Mpc), a location that places it on the outer ring of HI. The HI column of 2 \times 10^20 cm^-2 determined by the absorption in the X-ray spectrum of Ton 1480 is similar to the value from the HI map. Ultraviolet resonance line absorption is seen in Fe II, Mg I, and Mg II, with upper limits on the Mn II and Fe I lines. The heavy element abundances are significantly subsolar, with [Fe/H] = -2.0 and upper limits of [Mg/H] < -1.8 and [Mn/H] < -1.5. These results are similar to that found for DLA systems at z = 0.1--3, supporting the picture that they are produced in the outer part of disk galaxies.
Program listing for Friday