Early-type galaxies are dominantly metal-rich, of typically Solar metallicity, and usually enriched in SNe II products. Their compositions - both bulk metallicity and abundance ratios - depend on their mass and possibly on their environment. Their MDFs appear to violate 'simple' chemical-evolution models and therefore these galaxies suffer, like the Milky Way, from the G-dwarf problem. They appear to have complex star-formation histories: galactic winds and rapid star formation have apparently played crucial roles in their chemical evolution; and there is mounting evidence for recent star formation, suggesting that perhaps recent accretion or mergers are playing a role. Better understanding of their nucleosynthetic properties would be very helpful to disentangle these histories.
The future for understanding the nucleosynthetic histories of early-type galaxies is bright. Serven etal. (2005) have developed 54 new indices over a wide wavelength range in the optical that will help to determine C, N, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Sr and Ba abundances. A significant computational effort is under way by Worthey and collaborators (including the author), the intention being to produce fully self-consistent stellar-interior and -atmosphere models (and emergent spectra) to take advantage of these indices and their predecessors, the Lick/IDS indices. At the same time, line-strength measurements are being pursued both with two-dimensional spectrographs like SAURON to study local galaxies (e.g. Kuntschner et al. 2006) and with multi-slit spectrographs on large telescopes to study very distant ones (e.g. J0rgensen et al. 2005). New observations of nearby early-type galaxies with the ACS on the HST (such as the Lauer et al. and Worthey et al. studies of M32) will greatly improve our knowledge of their MDFs (and ages). It is hoped that the next generation of large telescopes will enable star-by-star chemical studies of the nearest elliptical galaxies!
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