Journal Article

The chemical evolution of dwarf spheroidal galaxies: dissecting the inner regions and their stellar populations

A. Marcolini, A. D'Ercole, G. Battaglia and B. K. Gibson

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 386, issue 4, pages 2173-2180
Published in print June 2008 | ISSN: 0035-8711
Published online April 2008 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2008.13175.x
The chemical evolution of dwarf spheroidal galaxies: dissecting the inner regions and their stellar populations

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Using three-dimensional hydrodynamical simulations of isolated dwarf spheroidal galaxies (dSphs), we undertake an analysis of the chemical properties of their inner regions, identifying the respective roles played by Type Ia supernovae (SNe Ia) and Type II supernovae (SNe II). The effect of inhomogeneous pollution from SNe Ia is shown to be prominent within two core radii, with the stars forming therein amounting to ∼20 per cent of the total. These stars are relatively iron-rich and α-element depleted compared to the stars forming in the rest of the galaxy. At odds with the projected stellar velocity dispersion radial profile, the actual three-dimensional one shows a depression in the central region, where the most metal-rich (i.e. [Fe/H]-rich) stars are partly segregated. This naturally results in two different stellar populations, with an anticorrelation between [Fe/H] and velocity dispersion, in the same sense as that observed in the Sculptor and Fornax dSphs. Because the most iron-rich stars in our model are also the most α depleted, a natural prediction and test of our model is that the same radial segregation effects should exist between [α/Fe] and velocity dispersion.

Keywords: hydrodynamics; stars: abundances; galaxies: abundances; galaxies: dwarf; galaxies: evolution; Local Group

Journal Article.  5836 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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