Topics figuring in this conference include limits to high metallicity, metallicity characteristics of stellar populations, [M/Fe] in bulges and discs, effects of metallicity on star formation and the initial mass function, its relation to planet formation, effects of high metallicity on stellar evolution, yields and galactic chemical evolution, metal-rich H ii regions and metallicities at high redshift.

I review the properties of starburst galaxies, compare the properties of the local ones with those of more distant starburts and examine their role in the metal enrichment of the interstellar medium and the intergalactic–intracluster medium. Metallicity is not an arrow of time and, contrary to current belief, metal-rich galaxies can also be found at high redshift.

We discuss the metallicity of massive stars in the Solar neighbourhood, comparing new results with those for the Sun. We find that, despite there being small systematic differences between various NLTE determinations of [O/H] in hot stars, there is reasonable agreement among results from various studies of nearby stars, with a value of 8.60±0.1 dex being implied. This is in good agreement with the latest Solar estimate based on three-dimensional models, and is in good agreement with recent estimates of the nebular oxygen abundance in Orion. We review the evidence for metal-rich massive stars in our own galaxy and in M31, concluding that there is little convincing evidence for supersolar [O/H] in massive stars in the Milky Way, while there is only limited evidence for mildly metal-rich regions in M31 with [O/H] relative to Solar of only +0.2. Discrepancies between stellar and nebular abundances at high metallicity can be traced to problems in calibrating the R23 index for H II regions in the metal-rich regime.

Elliptical galaxies probably host the most metal-rich stellar populations in the Universe. The processes leading to both the formation and the evolution of such stars are discussed in terms of a new multi-zone photochemical-evolution model, taking into account detailed nucleosynthetic yields, feedback from supernovae, Population-III stars and an initial infall episode. Moreover, the radial variations in the metallicity distributions of these stars are investigated using G-dwarf-like diagrams.

By comparing model predictions with observations, we derive a picture of galaxy formation in which the higher the mass of the galaxy, the shorter are the infall and the star-formation timescales. Therefore, the stellar component of the most massive and luminous galaxies might attain a metallicity Z ≥ Z⊙ in only 0.5 Gyr.

Each galaxy is created outside-in, i.e. the outermost regions accrete gas, form stars and develop a galactic wind very quickly, in contrast to the central core in which star formation can last up to ∼ 1.3 Gyr. This finding will be discussed in the light of recent observations of the galaxy NGC 4697 which clearly exhibits a strong radial gradient in the mean stellar [〈Mg/Fe〉] ratio.

It is currently impossible to determine the abundances of the stellar populations star by star in dense stellar systems more distant than a few megaparsecs. Therefore, methods to analyse the composite light of stellar systems are required. I review recent progress in determining the abundances and abundance ratios of early-type galaxies. I begin with ‘direct’ abundance measurements: colour–magnitude diagrams of stars and planetary nebulae in nearby early-type galaxies. I then give an overview of ‘indirect’ abundance measurements: inferences from stellar-population models, with an emphasis on cross-checks with ‘direct’ methods. I consider the variations of early-type galaxy abundances as a function of mass, age and environment in the local Universe. I conclude with a list of continuing difficulties in the modelling that complicate the interpretation of integrated spectra and I look ahead to new methods and new observations.

After a review of the many effects of metallicity on the evolution of rotating and non-rotating stars, we discuss the consequences of a high metallicity for massive-star populations and stellar nucleosynthesis. The most striking effect of high metallicity is to enhance the amount of mass lost by stellar winds. Typically, at a metallicity of Z = 0.001 only 9% of the total mass returned by non-rotating massive stars is ejected by winds (91% by supernova explosions), whereas at Solar metallicity this fraction may amount to more than 40%. High metallicity favors the formation of Wolf–Rayet stars and Type-Ib supernovae, but militates against the occurrence of Type-Ic supernovae. We estimate empirical yields of carbon on the basis of the observed population of WC stars in the Solar neighborhood, and obtain that WC stars eject 0.2%–0.4% of the mass initially locked into stars in the form of newly synthesized carbon. Models give values well in agreement with these empirical yields. Chemical-evolution models indicate that such carbon yields may have an important impact on the abundance of carbon at high metallicity.

The search for consistency between nebular and massive-star abundances has been a longstanding problem. I briefly review what has been done regarding this topic, also presenting a recent study focused on the Orion nebula: the O and Si stellar abundances resulting from a detailed and fully consistent spectroscopic analysis of the group of B stars associated with the Orion nebula are compared with the most recent nebular gas-phase results.

We present results from comparisons of elemental abundances and dust content between damped Lyman-alpha (DLA) absorbers and gamma-ray-burst (GRB) afterglows, as determined by absorption-line spectroscopy. Our sample of DLA absorbers includes the results from 76 quasar spectra taken with the HIRES spectrograph of the Keck observatory, from which we obtain a sample of 38 DLA absorbers in the redshift range 2 < z < 4. The GRB absorption lines were obtained in collaboration with the Caltech Carnegie NOAO GRB collaboration, in which rapid spectroscopy is obtained from newly discovered GRBs, to obtain high-quality optical spectra. We present results of O, N, C, Si, Zn, Cr, and C II*/C II ratios from a “core sample” of 15 of the best of the DLA absorbers, and detailed analysis of GRB 051111 and GRB 050505, which are at redshifts of z = 1.549 and 4.275, respectively. From our analysis we can see trends in the DLA dust content, and in [C/H], [N/H] and [O/H] values as a function of DLA redshift, as well as evidence for dust formation and highly excited dense gas within the disks of GRB host galaxies.

Recent progress in the study of the various proposed SN Ia-progenitor scenarios is reviewed. We discuss the effects of rotation on the evolution of SN Ia progenitors, in particular the stabilization of helium-shell burning and the increase of the Chandrasekhar limit. The latter may have been confirmed by a recent analysis of an overluminous SN 2003fg. For the evolution of CO white dwarf mergers, we discuss new arguments in favor of obtaining Type-Ia SNe from those systems, in contrast to the previous consensus. We onsensus. We address the issue of SN Ia delay times, and the dependence of average SN Ia properties on the type of host galaxy, in the light of recent observations and progenitor models, and derive implications for SN Ia yields.

This review summarizes the properties of the stellar population in bulges observed in nearby and distant spiral galaxies. Particular emphasis is placed on comparison with elliptical galaxies, when possible. The sample-selection criteria and choices in data analysis are addressed when they may be involved in discrepancies among published results.

We argue that the discrepancies observed in H ii regions between abundances derived from optical recombination lines (ORLs) and collisionally excited lines (CELs) might well be the signature of a scenario of the enrichment of the interstellar medium (ISM) proposed by Tenorio-Tagle (1996). In this scenario, the fresh oxygen released during massive supernova explosions is confined within the hot superbubbles as long as supernovae continue to explode. Only after the last massive supernova explosion does the metal-rich gas start to cool down and fall onto the galaxy in the form of metal-rich droplets. Full mixing of these metal-rich droplets and the ISM occurs during photoionization by the next generations of massive stars. During this process, the metal-rich droplets give rise to strong recombination lines of the metals, leading to the observed ORL–CEL discrepancy.

Several spectroscopic studies have shown that stars with giant planets are particularly metal-rich compared with average field stars. In this paper we review the most recent results concerning the study of the chemical abundances of planet-host stars. Abundance distributions for several elements are presented or discussed, including those of iron-peak and alpha-elements, and the light elements lithium (both 7Li and 6Li) and beryllium. The impact of these results on the theories of planet formation and evolution is discussed.

From stellar-evolution models and from observations of Wolf–Rayet stars it is known that massive stars are releasing metal-enriched gas during their Wolf–Rayet phase by means of strong stellar winds. Although H ii-region spectra serve as diagnostics to determine the present-day chemical composition of the interstellar medium, it is not yet reliably known to what extent the diagnostic H ii gas is already contaminated by chemically processed stellar-wind matter. In a recent paper, we therefore analyzed our models of radiation-driven and wind-blown H ii bubbles around an isolated 85M⊙ star of originally Solar metallicity with respect to its chemical abundances. Although the hot stellar-wind bubble (SWB) is enriched with 14N during the WN phase and even more so with 12C and 16O during the WC phase of the star, we found that at the end of the stellar lifetime the mass ratios of the traced elements N and O in the warm ionized gas are insignificantly higher than Solar, whereas an enrichment of 22% above Solar is found for C. The transport of enriched elements from the hot SWB to the cool gas occurs mainly by means of mixing of hot gas with cooler at the back side of the SWB shell.

We present a spectrophotometric study of circumnuclear star-forming regions (CNSFRs) in the early-type spiral galaxies NGC 2903, NGC 3351 and NGC 3504, all of them of over Solar metallicity according to standard empirical calibrations. A detailed determination of their abundances is performed after careful subtraction of the very prominent underlying stellar absorption. It is found that most regions exhibit the highest abundances in H II-region-like objects. The relative N/O and S/O abundances are discussed. It is also shown that CNSFRs, as a class, segregate from the disk H II region family, clustering around smaller “softness parameter” – η′ – values, and therefore higher ionizing temperatures.

We present a detailed study on the kinematics of metal-rich stars with and without planets, and their relation with the Hyades, Sirius and Hercules dynamical streams in the Solar neighbourhood. We compare the kinematic behaviour of known planet-host stars with that of the remaining targets belonging to the CORALIE volume-limited sample, in particular its metal-rich population. The high average metallicity of the Hyades stream is confirmed. The planet-host targets exhibit a kinematic behaviour similar to that of the metal-rich comparison subsample, rather than to that of the comparison sample as a whole, thus supporting the hypothesis of a primordial origin for the metal excess observed in stars with known planetary companions. According to the scenarios proposed as an explanation for the dynamical streams, systems with giant planets could have formed more easily in metal-rich inner Galactic regions

We discuss theoretical predictions and observational findings obtained for radiatively driven winds of massive stars, with emphasis on their dependence on metallicity. If these winds are not strongly clumped or the clumping properties are independent of metallicity z, theory and observations agree very well, and mass-loss rates and terminal velocities scale as Ṁ ∝ z0.62±015 and υ∞ ∝ z0.13, respectively. This dependence could be validated only for winds with Solar and subsolar abundances, due to the lack of supersolar-metallicity test cases. The actual values for the mass-loss rates are uncertain, due to unknown clumping properties of the wind, and currently accepted numbers might be overestimated by factors in between ∼2 and 10.