Book contents
- Frontmatter
- Contents
- List of contributors
- Preface
- Part I Abundances in the Galaxy: field stars
- Part II Abundances in the Galaxy: Galactic stars in clusters, bulges and the centre
- Part III Observations – abundances in extragalactic contexts
- Part IV Stellar populations and mass functions
- Part V Physical processes at high metallicity
- Part VI Formation and evolution of metal-rich stars and stellar yields
- 36 Massive-star evolution at high metallicity
- 37 Supernovae in Galactic evolution: direct and indirect metallicity effects
- 38 Progenitor evolution of Type-I supernovae: evolution and implications for yields
- 39 Star formation in the metal-rich Universe
- 40 Metallicity of Solar-type main-sequence stars: seismic tests
- 41 Chemical-abundance gradients in early-type galaxies
- 42 Oxygen-rich droplets and the enrichment of the interstellar medium
- Part VII Chemical and photometric evolution beyond Solar metallicity
41 - Chemical-abundance gradients in early-type galaxies
Published online by Cambridge University Press: 02 December 2009
- Frontmatter
- Contents
- List of contributors
- Preface
- Part I Abundances in the Galaxy: field stars
- Part II Abundances in the Galaxy: Galactic stars in clusters, bulges and the centre
- Part III Observations – abundances in extragalactic contexts
- Part IV Stellar populations and mass functions
- Part V Physical processes at high metallicity
- Part VI Formation and evolution of metal-rich stars and stellar yields
- 36 Massive-star evolution at high metallicity
- 37 Supernovae in Galactic evolution: direct and indirect metallicity effects
- 38 Progenitor evolution of Type-I supernovae: evolution and implications for yields
- 39 Star formation in the metal-rich Universe
- 40 Metallicity of Solar-type main-sequence stars: seismic tests
- 41 Chemical-abundance gradients in early-type galaxies
- 42 Oxygen-rich droplets and the enrichment of the interstellar medium
- Part VII Chemical and photometric evolution beyond Solar metallicity
Summary
We present long-slit spectra for 11 early-type galaxies observed with the Keck telescope. We measure rotation-velocity and velocity-dispersion profiles together with 20 Lick line-strength gradients. Gradients of indices are transformed into ages, metallicities and [α/Fe] using stellar-population models that take into account variations in chemical-abundance ratios. We find that the line-strength gradients are mainly due to radial variations of metallicity, although small gradients of [α/Fe] and age are also present. Contrary to what is expected in simple collapse models, galaxies in our sample have both positive and negative [α/Fe] profiles. This rules out a solely inside-out or outside-in formation mechanism for all early-type galaxies. Metallicity gradients correlate with the shape of the isophotes and the rotational velocity but do not correlate with the mass of the galaxies. Galaxies with younger populations in their centres have steeper metallicity gradients. Our results suggest a scenario whereby galaxies form through the merger of smaller structures and the degree of dissipation during those mergers increases when the masses of the progenitor galaxies decrease.
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- The Metal-Rich Universe , pp. 403 - 408Publisher: Cambridge University PressPrint publication year: 2008