Star clusters Galactic

P. North, F. Royer, C. Melo et al. New homogeneous vsinf determinations for B stars in galactic open clusters . In Stellar Rotation, IAIJ Symp. 215, ed. by A. Maeder, P. Eenens (in press)... 

Star Clusters in the Galactic Anticenter Stellar Structure New Radial Velocities Sc Metallicities... 

Open clusters (OCs) are important tools both for stellar and for galactic astrophysics, as tests of stellar evolution theory for low and intermediate mass stars and as tracers of the Galactic disk properties. Since old OCs allow us to probe the lifetime of the Milky Way disk, up to about 10 Gyr ago, they can be used to study the disk evolution with time, and in particular its chemical history. 

Abstract. In this contribution we present the results based on high-resolution spectra of 45 clump stars of the Galactic field. The main atmospheric parameters and abundances of 12C, 13C, N, O and other mixing sensitive chemical elements were investigated. Elemental ratios in the sample of field stars are compared to the results available for evolved stars in open clusters and to the theoretical prediction of extra mixing in stellar interiors. 

Abundance Variations in the Galactic Disk Planetary Nebulae, Open Clusters and Field Stars... 

Fig. 1. Oxygen abundances as a function of the activity index, Rx, derived from X-ray data (left-hand panels) and the excitation temperature Texc (right-hand panels). The bottom panels show the difference between [O/Fe] yielded by the OI triplet at about 7774 A and the [OI] A6300 line. Filled circles RS CVn binaries ([2] and [3]), filled squares field subgiants [3], filled triangles Pleiades stars, open triangles Hyades stars, open circles, squares and hexagons disk dwarfs. The source of the literature data for the open cluster and Galactic disk stars can be found in [4].

Abstract. A review is presented on abundance determinations in stars of the Galactic bulge, both in the field and in globular clusters. Previous low-resolution spectroscopy results are revised. Recent high resolution and high S/N spectroscopy results based on Keck-Hires, Gemini-Phoenix and VLT-UVES data are presented. Finally, recent analyses of FLAMES data are discussed. 

Our analysis allows also to estimate the incidence of (3 Cephei stars in the LMC and SMC. They constitute of about 0.3% in the LMC, that is an order of magnitude more than in the SMC and about two orders less than in Galactic young clusters. 

Table 1 lists our abundances of Fe, C, O and a-elements for the observed clusters. An overall excess of a-elements is shared by all the clusters up to solar metallicity, consistent with SNell being responsible for the gas enrichment. Our findings are also in good agreement both with all previous high resolution studies (see [2], [3], [6]) and with recent abundance determinations for field stars in the Galactic Bulge (see [10]). 

Fig. 1. Plot of Ca, Mg and Na ratios over Fe in Fornax GC (filled symbols) and Fornax field (empty squares) [2] stars. We show data for individual stars in cluster 1 (triangles), cluster 2 (circles) and cluster 3 (diamonds). The other points comes from 2 review papers, the small dots are galactic stars from [3] and the small open circles are Galactic GCs, from [4]. The asterisk are M15 stars, our reference cluster.

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