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Helium has been proposed as the key element to interpret the observed multiple main sequences (MS), subgiant branches (SGB) and red giant branches (RGB), as well as the complex horizontal branch (HB) morphology in Globular Clusters (GC).…

Astrophysics of Galaxies · Physics 2015-05-13 S. Villanova , G. Piotto , R. G. Gratton

The HST UV Survey of Globular Clusters (GCs) has investigated GCs and their stellar populations. In previous papers of this series we have introduced a pseudo two-color diagram, "chromosome map" (ChM), that maximises the separation between…

Solar and Stellar Astrophysics · Physics 2019-05-29 A. F. Marino , A. P. Milone , A. Renzini , F. D'Antona , J. Anderson , L. R. Bedin , A. Bellini , G. Cordoni , E. P. Lagioia , G. Piotto , M. Tailo

The ejecta of the first probably very massive stars polluted the Big Bang primordial element mix with the first heavier elements. The resulting ultra metal-poor abundance distribution provided the initial conditions for the second stars of…

Astrophysics · Physics 2007-08-30 Falk Herwig

AGB stars have long been held responsible for the important star-to-star variations in light elements observed in Galactic globular clusters. We analyse the main impacts of a first generation of rotating intermediate-mass stars on the…

Solar and Stellar Astrophysics · Physics 2015-05-13 T. Decressin , C. Charbonnel , L. Siess , A. Palacios , G. Meynet , C. Georgy

Globular clusters contain many stars with surface abundance patterns indicating contributions from hydrogen burning products, as seen in the anti-correlated elemental abundances of e.g. sodium and oxygen, and magnesium and aluminium.…

Solar and Stellar Astrophysics · Physics 2013-02-05 Robert G. Izzard , Selma E. de Mink , Onno R. Pols , Norbert Langer , Hugues Sana , Alex de Koter

We report the first high resolution, detailed abundances of 21 elements for giants in the Galactic bulge/bar within $1^\circ$ of the Galactic plane, where high extinction has rendered such studies challenging. Our high S/N and…

Information on globular clusters (GC) formation mechanisms can be gathered by studying the chemical signature of the multiple populations that compose these stellar systems. In particular, we are investigating the anticorrelations among O,…

Solar and Stellar Astrophysics · Physics 2015-11-04 A. Bragaglia , E. Carretta , A. Sollima , P. Donati , V. D'Orazi , R. G. Gratton , S. Lucatello , C. Sneden

Almost all globular clusters investigated exhibit a spread in their light element abundances, the most studied being a Na:O anticorrelation. In contrast, open clusters show a homogeneous composition and are still regarded as Simple Stellar…

Astrophysics of Galaxies · Physics 2015-06-05 D. Geisler , S. Villanova , G. Carraro , C. Pilachowski , J. Cummings , C. I. Johnson , F. Bresolin

NGC1851 possibly shows a spread in [Fe/H], but the relation between this spread and the division in the SGB is unknown. We obtained blue (3950-4600 A) intermediate resolution (R~8,000) spectra for 47 stars on the bright and 30 on the faint…

Solar and Stellar Astrophysics · Physics 2015-06-05 R. G. Gratton , S. Villanova , S. Lucatello , A. Sollima , D. Geisler , E. Carretta , S. Cassisi , A. Bragaglia

We analyse the population of bright star clusters in the interacting galaxy pair NGC 4038/39 detected with HST WFPC1 by Whitmore & Schweizer (1995) using our spectrophotometric evolutionary synthesis models for various initial…

Astrophysics · Physics 2007-05-23 Uta Fritze-v. Alvensleben

Young open clusters (t<200 Myr) have been observed to exhibit several peculiarities in their chemical compositions, from a slightly sub-solar iron content, super-solar abundances of some atomic species (e.g. ionised chromium), and atypical…

In the past decade, the notion that globular clusters (GCs) are composed of coeval stars with homogeneous initial chemical compositions has been challenged by growing evidence that they host an intricate stellar population mix, likely…

We present a comparison of high-resolution, integrated-light, detailed chemical abundances for Galactic and extragalactic globular clusters in both massive galaxies and dwarf galaxies. We include measurements of Fe, Ca, Si, Na, and Al for…

Cosmology and Nongalactic Astrophysics · Physics 2013-02-27 J. E. Colucci , R. A. Bernstein , A. McWilliam , J. G. Cohen

The chemical processes during the Asymptotic Giant Branch (AGB) evolution of intermediate mass single stars predict most of the observations of the different populations in Globular Clusters although some important issues still need to be…

Astrophysics of Galaxies · Physics 2014-01-24 N. Mennekens , D. Vanbeveren , J. P. De Greve

This research forms part of an investigation into heavy element abundances in Asymptotic Giant Branch (AGB) stars in various stellar environments. Seven giant stars in the southern globular cluster 47 Tuc have been observed using the…

Astrophysics · Physics 2008-11-26 E. C. Wylie , P. L. Cottrell , C. A. Sneden , J. C. Lattanzio

We present the abundances of N in a sample of 62 stars on the red giant branch (RGB) in the peculiar globular cluster NGC 1851. The values of [N/Fe] ratio were obtained by comparing the flux measured in the observed spectra with that from…

Astrophysics of Galaxies · Physics 2014-03-05 Eugenio Carretta , Valentina D'Orazi , Raffaele G. Gratton , Sara Lucatello

Concentration is one of the key dark matter halo properties that could drive the scatter in the stellar-to-halo mass relation of massive clusters. We derive robust photometric stellar masses for a sample of brightest central galaxies (BCGs)…

NGC 362 is a non-common Type II Galactic globular cluster, showing a complex pseudo two-color diagram or 'chromosome map'. The clear separation of its stellar populations in the color-magnitude diagram and the distribution of the giant…

Astrophysics of Galaxies · Physics 2022-07-13 C. Vargas , S. Villanova , D. Geisler , C. Muñoz , L. Monaco , J. O'Connell , Ata Sarajedini

The presence of impurities in the neutron star crust is known to affect in an important way the thermal and electrical conductivity of the star. In this work, we explore the possibility that such impurities might arise from the simultaneous…

We present detailed chemical abundances in 8 clusters in the Large Magellanic Cloud (LMC). We measure abundances of 22 elements for clusters spanning a range in age of 0.05 to 12 Gyr, providing a comprehensive picture of the chemical…

Astrophysics of Galaxies · Physics 2015-06-03 J. E. Colucci , R. A. Bernstein , S. A. Cameron , A. McWilliam