相关论文: The Na-O anticorrelation in horizontal branch star…

We derived atmospheric parameters and elemental abundances of Fe, O and Na for about 120 red giant stars in the Galactic globular cluster NGC 2808. Our results are based on the analysis of medium-high resolution (R=22000-24000) GIRAFFE…

We studied the Na-O anti-correlation from moderately high resolution spectra for 35 stars on the blue HB (BHB), one RR Lyrae, and 55 stars are on the red HB (RHB) of NGC1851. We also derived abundances for He and N in BHB stars, and Ba and…

To check the impact of the multiple population scenario for globular clusters on their HB, we present an analysis of the composition of 110 red HB (RHB) stars in 47 Tucanae and of 61 blue HB (BHB) and 30 RHB stars in M5. In 47 Tuc we found…

We present an abundance analysis of 96 horizontal branch (HB) stars in NGC2808, a globular cluster exhibiting a complex multiple stellar population pattern. These stars are distributed in different portions of the HB and cover a wide range…

We obtained high-resolution spectra for 94 candidate stars belonging to the HB of M22 with FLAMES. The HB stars we observed span a restricted temperature range (7,800<Teff<11,000 K), where about 60% of the HB stars of M22 are. Within our…

We used the multifiber spectrograph FLAMES on the ESO Very Large Telescope UT2 to derive atmospheric parameters, metallicities and abundances of O and Na for 79 red giant stars in the Galactic globular cluster NGC 6218 (M 12). We analyzed…

We used FLAMES+GIRAFFE (Medusa mode) at the VLT to obtain moderately high resolution spectra for 30 red horizontal branch (RHB) stars, 4 RR Lyrae variables, and 17 blue horizontal branch (BHB) stars in the low-concentration, moderately…

We present abundances of Fe, Na, and O for 1409 red giant stars in 15 galactic globular clusters, derived from the homogeneous analysis of high resolution FLAMES/GIRAFFE spectra. Combining the present data with previous results, we obtained…

We are studying the Na-O anticorrelation in several globular clusters of different Horizontal Branch (HB) morphology in order to derive a possible relation between (primordial) chemical inhomogeneities and morphological parameters of the…

He has been proposed as a key element to interpret the observed multiple MS, SGB, and RGB, as well as the complex horizontal branch (HB) morphology. Stars belonging to the bluer part of the HB, are thought to be more He rich (\Delta Y=0.03…

We find a strong correlation between the extension of the Na-O anticorrelation observed in red giant branch (RGB) stars and the high temperature extension of the horizontal branch (HB) blue tails of Galactic globular clusters (GCs). The…

We present the abundance analysis for a sample of 17 red giant branch stars in the metal-poor globular cluster M28 based on high resolution spectra. This is the first extensive spectroscopic study of this cluster. We derive abundances of O,…

Due to their extreme helium abundance, the multiple stellar populations of the globular cluster NGC 2808 have been widely investigated from a photometric, spectroscopic, and kinematic perspective. The most striking feature of the…

We have carried out high-precision photometry on a large number of archival HST images of the Galactic globular cluster NGC 6752, to search for signs of multiple stellar populations. We find a broadened main sequence, and demonstrate that…

Nearly all Galactic globular clusters host stars that display characteristic abundance anti-correlations, like the O-rich/Na-poor pattern typical of field halo stars, together with O-poor/Na-rich additional components. A recent…

We present an accurate analysis of the peculiar Horizontal Branch (HB) of the massive Galactic globular cluster NGC 2808, based on high-resolution far-UV and optical images of the central region of the cluster obtained with HST. We confirm…

Large star-to-star abundance variations are direct evidence of multiple stellar populations in Galactic globular clusters (GCs). The main and most widespread chemical signature is the anti-correlation of the stellar Na and O abundances. The…

Recent UV observations of the globular cluster NGC2808 (Brown et al. 2001) show a significant population of hot stars fainter than the zero-age horizontal branch (``blue hook'' stars), which cannot be explained by canonical stellar…

Pseudo two-colour diagrams or Chromosome maps (ChM) indicate that NGC 2808 host five different stellar populations. The existing ChMs have been derived by the Hubble Space Telescope photometry, and comprise of stars in a small field of view…

The aim of the present work is to determine accurate metallicities for a group of red giant branch stars in the field of the bulge Globular Cluster NGC 6441. This is the third paper of a series resulting from a large project aimed at…