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Paper: Ellipticals Before Gas Loss
Volume: 147, Abundance Profiles: Diagnostic Tools for Galaxy History
Page: 259
Authors: McCall, Marshall L.; Richer, Michael G.; Stasinska, Grazyna
Abstract: Recent direct measurements of oxygen abundances in elliptical galaxies, spiral bulges, and dwarf spheroidals make possible solutions for the free parameters describing the chemical evolution of dynamically hot systems (DHS's) within the framework of the supernovae-driven wind model for gas loss. Gas fractions just prior to the onset of steady gas loss, the yield of oxygen, and the nature of flows during the gas-rich phase have been determined for seven systems by fitting oxygen abundances and their dispersions via downhill simplex with simulated annealing. Even before the onset of a wind, DHS's could not have been closed. Instead, outflows appear to have predominated. Dwarf spheroidals and ellipticals/bulges must have been energetically different to explain the apparent break between their chemical properties. Results for gas fractions and flow rates enable the determination of initial masses, and ultimately will lead to a reliable estimate of the total amount of gas contributed to the intergalactic medium by DHS's.
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