Abstract
We explore the formation of α-enhanced and metal-rich stellar populations in the nuclei of luminous ellipticals under the assumption of two extreme galaxy formation scenarios based on hierarchical clustering, namely a fast clumpy collapse and the merger of two spirals. We investigate the parameter space of the star formation time-scale, the slope of the initial mass function (IMF) and stellar yields. In particular, the latter add a huge uncertainty in constraining time-scales and IMF slopes. We find that—for Thielemann, Nomoto & Hashimoto nucleosynthesis—in a fast clumpy collapse scenario an [α/Fe] overabundance of ∼ 0.2 dex in the high-metallicity stars can be achieved with a Salpeter IMF and star formation time-scales of the order 109 yr. The scenario of two merging spirals that are similar to our Galaxy, instead, fails to reproduce the α-enhanced abundance ratios in the metal-rich stars, unless the IMF is flattened during the burst ignited by the merger. This result is independent of the burst time-scale. We suggest that abundance gradients give hints to distinguish between the two extreme formation scenarios considered in this paper.
Original language | English |
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Pages (from-to) | 537-548 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 302 |
Issue number | 3 |
Early online date | 1 Jan 1999 |
DOIs | |
Publication status | Published - 21 Jan 1999 |
Keywords
- galaxies : elliptical and lenticular, cD
- galaxies : formation
- galaxies : luminosity function, mass function
- galaxies : stellar content