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The Galactic Anticenter Stellar Structure (GASS) has been identified with excess surface densities of field stars in several large area sky surveys, and with an unusual, string-like grouping of star clusters. Some members of the cluster grouping have radial velocities (RVs) consistent with the observed GASS velocity-longitude trend. We provide new RV measurements of stars in six clusters that have been suggested to be associated with the GASS. We show that the RVs of at least four clusters are consistent with the previously measured RV trend for GASS. We also derive spectroscopic metallicities for four clusters, and provide an improved age-metallicity relation for the clusters apparently associated with GASS.

Strömgren photometry is a powerful tool to study abundance variations in globular clusters through the and indices. This is because the NH (3360Å) and CN–bands (4215Å) are present in the and filters, respectively. In [1] it was shown that in NGC 6752 the observed star–to–star variations in the index correlates very strongly with the abundance of nitrogen as measured through the strength of the NH band. As part of a project to study globular clusters with Strömgren photometry we have observed 20 clusters from the Nordic Optical Telescope on La Palma and the Danish 1.54m telescope on La Silla. All clusters in our sample show star–to–star variations in their index indicating that they all have large variations in their nitrogen abundance. The variations are seen for stars with luminosities ranging from the cluster turnoff to the brightest RGB

High resolution ( ≳ 40 000) and high spectra have been acquired with UVES on the VLT-Kueyen (Paranal Observatory, ESO Chile) for several MS turno. stars ( ~ 17 mag) and subgiants at the base of the RGB ( ~ 16 mag) in three globular clusters (NGC 6397, NGC 6752 and 47 Tuc/NGC 104) at different metallicities (respectively [Fe/H] ≃ −2.0;−1.5;−0.7). A sample of 25 field halo subdwarves has also been taken with equal resolution and higher . These data have been used in the framework of the ESO-LP “Globular Cluster Ages, Distances and Metallicities” to determine the abundances of several heavy elements in these three clusters: Sr, Y, Ba, and Eu. These are the first abundance determinations of neutron-capture elements for such an extended sample of scarcely evolved stars. These values together with the [Ba/Eu] and [Sr/Ba] abundance ratios have been used to test the self-enrichment scenario. A comparison is done with field halo stars and other well known globular clusters in which heavy elements have already been measured in the past at least in bright giants ( ~ 11−12 mag). Our results show clearly that globular clusters have been uniformly enriched by – and –process syntheses, and that even if globular clusters present usually “abundance anomalies” for some of the light metals, most of them exhibit neutron-capture element abundance patterns that are very similar to those of field halo stars at similar metallicities.

Large and Small Magellanic Clouds (LMC and SMC) are less abundant in heavy elements than the Galaxy ( = 0.008, = 0.004), but they have relatively well-known distance and small interstellar absorption. These galaxies are among the best objects for the study of dependencies of different astrophysical parameters on metallicity.

We present a progress report of our work on the galactic bulge. It is based on a sample of clump giants in Baade’s window with high-resolution spectroscopic data obtained with FLAMES in the framework of the Paris Observatory GTO time. The final aim of this programme is to determine 1) the metallicity distribution, 2) the abundance ratios of α-elements, of - and - process elements for a statistically significant sample, 3) the mean kinematical parameters of the bulge populations and their possible correlation with metallicity.

The chemical composition of B12, a Be star in the SMC cluster NGC330, is analysed using high-resolution UVES/VLT spectra and the non-LTE model atmosphere code tlusty. A differential analysis relative to a SMC standard star AV304 revealed (1) a general under-abundance of metals compared with that expected for the SMC, and (2) the lack of nitrogen enhancement. The former is attributed to the presence of a disk, and its contribution to the overall emission is estimated. Possible explanations for the lack of rotational mixing in the apparently rapidly rotating star are discussed.

Detailed elemental abundance studies of globular clusters may provide strong constraints on the Galaxy formation picture. For example, a metallicity gradient would imply that the Galaxy formed via a slow dissipational process. A constant and enhanced [α/Fe] versus [Fe/H] relation may indicate that the globular clusters must have formed simultaneously within a couple of gigayears (Wyse & Gilmore 1988; Carney 1996), so that their proto-cluster clouds were not contaminated by SNe Ia products. The abundance ratio of -process elements to -process elements, such as [Ba/Eu] and [La/Eu], as a function of metallicity in globular cluster systems, may also suggest how rapidly they were polluted by the low- or intermediate-mass stars before they formed. In spite of the importance of the chemical abundance studies, high resolution spectroscopic studies of the globular clusters near the Galactic center have not been performed due to the observational limitations set by large interstellar reddening.

We present the results of an observational campaign undertaken to assess the influence of the iron content on the Cepheid Period-Luminosity relation. Our data indicate that this dependence is not well represented by a simple linear relation. Rather, the behaviour is markedly non monotonic, with the correction peaking at about solar metallicity and declining for higher and lower values of [].

In the present work we report abundance ratios for Ca, Ti, Si, Ni, Cr and V for metal-rich stars belonging to the bulge-like sample (e.g. [5]) with metallicities ranging [Fe/H] = 0.0 to +0.55 dex. The bulge-like sample contains very old stars with ages ~ 10 Gyr, and highly eccentric orbits, with probable origin in the inner disk or in the bulge of the Galaxy. Previous works in the same metallicity range indicate an increasing trend with metallicity for Si, Ni and Ti, and a flat trend for Ca, Cr and V. In our sample, iron-peak group element ratios show no trend with metallicity and overlap with that of the disk, while α-elements Si, Ca and Ti show slightly underabundant behavior when compared to thin disk samples.

We present abundance measurements, based on high resolution optical spectroscopic data obtained with the UVES at VLT, for 10 stars in the blue horizontal branch (BHB) of the Galactic globular cluster NGC 1904 (M79). In agreement with previous findings for other clusters, we obtain normal abundances for stars cooler than Te. ~ 11000 K, and largely anomalous abundances for hotter stars: large He depletions and overabundances of Fe, Ti, Cr, P and Mn. The abundances of Mg, Si and Ca are roughly normal, in the hot stars as well as in the cooler ones. This abundance pattern can be attributed to the onset of diffusion and to radiation pressure in the stable atmospheres of hot HB stars. A possibly related discontinuity in the stellar rotation rate seems also to occur at Te. ~ 11000 K.