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Paper: Evolution within the Hubble Sequence: Clues from the Abundances
Volume: 147, Abundance Profiles: Diagnostic Tools for Galaxy History
Page: 237
Authors: Pfenniger, Daniel
Abstract: Currently there are three quite different views about galaxy evolution, each one improving the previous state of knowledge:\\ (1) The older one (``ELS'') in which galaxies form by collapse early, quickly, and quasi-synchronously (during the ``galaxy formation epoch''), ending the dynamically active period; subsequent galaxy evolution is merely a matter of stellar formation processes in a rigid potential.\\ (2) An alternative one (``SZ'') in which disks are viewed as forming inside out over an extended period of time. Galaxy evolution occurs without important internal dynamical instabilities.\\ (3) The slowly emerging picture, after 40 years of N-body simulations and the obvious evidences from recent high-z observations: galaxies evolve both dynamically and chemically over most of the Hubble time in a widely asynchronous way at different speeds, depending on the environment. The Hubble sequence, from late to early types, appears to represent a broad description of the general aging process. In such circumstances, abundances appear especially useful to learn about galaxies in cases of brief, Myr time-scale events involving both dynamics and star formation.
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