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The metallicity gradient and the stellar distribution within the Local Group dwarf galaxy NGC 6822 has been studied photometrically using asymptotic branch stars (AGB). In order to study the stellar and metallicity distribution, the carbon-…

Solar and Stellar Astrophysics · Physics 2010-11-22 L. F. Sibbons , M. -R. L. Cioni , M. Irwin , M. Rejkuba

As ancient, gravitationally bound stellar populations, globular clusters are abundant, vibrant laboratories characterized by high frequencies of dynamical interactions coupled to complex stellar evolution. Using surface brightness and…

We explain the multiple populations recently found in the 'prototype' Globular Cluster (GC) NGC 2808 in the framework of the asymptotic giant branch (AGB) scenario. The chemistry of the five -or more- populations is approximately consistent…

Astrophysics of Galaxies · Physics 2016-03-09 F. D'Antona , E. Vesperini , A. D'Ercole , P. Ventura , A. P. Milone , A. F. Marino , M. Tailo

In order to account for the chemical composition of a stellar second generation (SG), Globular Clusters (GCs) evolution models based on the asymptotic giant branch (AGB) scenario so far included only the yields available for the massive AGB…

Astrophysics of Galaxies · Physics 2015-06-04 Annibale D'Ercole , Francesca D'Antona , Roberta Carini , Enrico Vesperini , Paolo Ventura

Our work focuses on the understanding of the origin of CNO-anomalies, which have been detected in several Galactic globular clusters (GCs). This study is based on a homogeneous data set of hundreds of medium resolution spectra of stars in…

Astrophysics · Physics 2009-11-13 Andrea Kayser , Michael Hilker , Eva K. Grebel , Philip G. Willemsen

This paper presents results from wide-field imaging of the globular cluster (GC) systems of five intermediate-luminosity (M_V ~-21 to -22) early-type galaxies. The aim is to accurately quantify the global properties of the GC systems by…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 Jonathan R. Hargis , Katherine L. Rhode

An abundance analysis based on a high-resolution spectrum is presented for a newly discovered post-AGB star in the globular cluster M79. The surprising result is that the iron abundance of the star is apparently about 0.6 dex less than that…

Solar and Stellar Astrophysics · Physics 2015-05-13 T. Sahin , David L. Lambert

The metal-rich Galactic globular cluster NGC 6366 is the fifth closest to the Sun. Despite its interest, it has received scarce attention, and little is known about its internal structure. Its kinematics suggests a link to the halo, but its…

Astrophysics of Galaxies · Physics 2018-03-30 Arthur A. Puls , Alan Alves-Brito , Fabíola Campos , Bruno Dias , Beatriz Barbuy

The stars in globular clusters are known to differ in their surface chemistry: the spectroscopic investigations in the last decades outlined the presence of star-to-star differences in the abundances of the light elements, up to aluminium…

Solar and Stellar Astrophysics · Physics 2017-05-24 Paolo Ventura , Roberta Carini , Francesca D'Antona

Recently, \citet{vitral2021does} detected a central concentration of dark objects in the core-collapsed globular cluster NGC 6397, which could be interpreted as a subcluster of stellar-mass black holes. However, it is well established…

This paper presents the chemical abundance analysis of 217 stars in the metal-poor globular cluster NGC 6752, distributed from the turn-off to the lower red giant branch. Aluminium and Lithium abundances were derived through spectral…

Solar and Stellar Astrophysics · Physics 2022-02-09 J. Schiappacasse-Ulloa , S. Lucatello , M. J. Rain , A. Pietrinferni

We have computed low-mass stellar models and synthetic spectra for an initial chemical composition that includes the full C-N, O-Na, and Mg-Al abundance anticorrelations observed in second generation stars belonging to a number of massive…

Solar and Stellar Astrophysics · Physics 2015-06-15 Santi Cassisi , Alessio Mucciarelli , Adriano Pietrinferni , Maurizio Salaris , Jason Ferguson

Long-lived stars in GCs exhibit chemical peculiarities with respect to their halo counterparts. In particular, Na-enriched stars are identified as belonging to a 2d stellar population born from cluster material contaminated by the H-burning…

Solar and Stellar Astrophysics · Physics 2016-01-27 C. Charbonnel , W. Chantereau

Asymptotic giant branch (AGB) stars play a key role in the enrichment of galaxies with heavy elements. Due to their large amplitude variability, the measurement of elemental abundances is a highly challenging task that has not been solved…

Solar and Stellar Astrophysics · Physics 2014-09-05 Thomas Lebzelter , Walter Nowotny , Kenneth H. Hinkle , Susanne Höfner , Bernhard Aringer

We present aluminium abundances for a sample of about 100 red giant stars in each of the Galactic globular clusters 47 Tuc (NGC 104) and M 4 (NGC 6121). We have derived homogeneous abundances from intermediate-resolution FLAMES/GIRAFFE…

Astrophysics of Galaxies · Physics 2015-06-12 Eugenio Carretta , Raffaele Gratton , Angela Bragaglia , Valentina D'Orazi , Sara Lucatello

Abundances of C, N, and O are determined in four bright red giants that span the known abundance range for light (Na and Al) and s-process (Zr and La) elements in the globular cluster NGC 1851. The abundance sum C+N+O exhibits a range of…

Solar and Stellar Astrophysics · Physics 2009-11-13 David Yong , Frank Grundahl , Francesca D'Antona , Amanda I. Karakas , John C. Lattanzio , John E. Norris

We recently discovered that NGC 3201 has characteristics that set it outside the current twofold classification scheme for Galactic globular clusters (GCs). Most GCs are mono-metallic and show light-element abundance variations (e.g., Na-O…

Solar and Stellar Astrophysics · Physics 2020-03-18 Bruno Dias , Ignacio Araya , João Paulo Nogueira-Cavalcante , Leila Saker , Ahmed Shokry

We present an analysis of the multiple stellar populations of the globular cluster NGC 1851. We used lower resolution spectra of giant stars to measure CN, CH, and calcium H & K spectral indices, and determine elemental abundances for…

Solar and Stellar Astrophysics · Physics 2016-10-31 Jeffrey D. Simpson , Sarah L. Martell , Colin A. Navin

The spectroscopic and photometric signals of the star-to-star abundance variations found in globular clusters seem to be correlated with global parameters like the cluster's metallicity, mass and age. Understanding this behaviour could…

Globular clusters have been recognized to host multiple stellar populations. A spectacular example of this is the massive cluster NGC2808, where multiple populations have been found along the horizontal branch (HB) and the main sequence…

Astrophysics of Galaxies · Physics 2015-05-30 R. G. Gratton , S. Lucatello , E. Carretta , A. Bragaglia , V. D'Orazi , Y. Al Momany