Based on observations collected with the Magellan Telescopes.

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Table 1 and Figs. 2, 4, 7-9, 13 are only available in electronic form at http://www.aanda.org

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... IRAF

IRAF is distributed by National Optical Astronomy Observatories, which is operated by the Association of Universities for Research in Astronomy, Inc., under contract to the National Science Foundation, USA.

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