Related papers: Lithium and proton-capture elements in globular cl…
The Na-O anticorrelation seen in almost all globular clusters ever studied using high-resolution spectroscopy is now generally explained by the primordial pollution from the first generation of the intermediate-mass asymptotic giant branch…
To alleviate the discrepancy between the prediction of the primordial lithium abundance in the universe and the abundances observed in Pop II dwarfs and subgiant stars, it has been suggested that the stars observable today have undergone…
HST has recently revealed that many among the most massive globular clusters harbor multiple stellar populations, and --most surprisingly-- some of them are extremely helium rich. How these clusters managed to generate such complex stellar…
The recent measurements of internal variations of helium in Galactic and extragalactic Globular Clusters (GCs) set binding constraints to the models of formation of Multiple Populations (MPs) in GCs, and gave rise, at the same time, to…
The new generation of 3D hydrodynamical model atmospheres have been employed to study the impact of a realistic treatment of stellar convection on element abundance determinations of globular cluster stars for a range of atomic and…
We propose that the abundance anomalies of proton-capture elements in globular clusters, such as the C-N, Na-O, Mg-Al and Na-F anti-correlations, were produced by super-massive stars with M ~ 10,000 Msun. Such stars could form in the…
Lithium is made up in the envelopes of massive Asymptotic Giant Branch (AGB) stars through the process of Hot Bottom Burning. In Globular Clusters, this processing is one possible source of the hot-CNO burning whose nuclear products are…
We demonstrate that among the potential sources of the primordial abundance variations of the proton-capture elements in globular-cluster stars proposed so far, such as the hot-bottom burning in massive AGB stars and H burning in the…
The behavior of lithium (Li) in Population I main sequence stars challenges standard stellar theory. Two phenomena stand out: the solar Li problem which extends to Li depletion in solar analogs and the Li dip observed in mid-F stars within…
Halo globular clusters pose four succinct issues that must be solved in any scenario of their formation: single-age, single metallicity stellar populations; a lower limit ([Fe/H] ~ -2.3) to their average metallicity; comprising only 1% of…
Star-to-star variations in abundances of the light elements carbon, nitrogen, oxygen, and sodium have been observed in stars of all evolutionary phases in all Galactic globular clusters that have been thoroughly studied. The data available…
Recent WMAP observations indicate that the primordial abundance of lithium should have been 2-4 times higher than the value measured in low-metallicity stars. We show that this discrepancy can be explained by the process of ambipolar…
Almost several decades after the discovery of the first multiple populations in galactic globular clusters (GC) the debate on their formation is still extremely current and NGC2808 remains one of the best benchmark to test any scenario for…
We briefly summarize the impact of the chemical peculiarities associated to the multiple population phenomenon in Galactic Globular Clusters, on the evolutionary properties and spectral energy distribution of second generation stars, in…
Several scenarios have been proposed to explain the presence of multiple stellar populations in globular clusters. Many of them invoke multiple generations of stars to explain the observed chemical abundance anomalies, but it has also been…
Most globular clusters in the local group show multiple stellar populations, a pattern defined by variations of several light elements, with some also displaying dispersions in heavy elements. Since helium is the most immediate product of…
A self-consistent model of the chemical evolution of the globular cluster NGC 6752 is presented to test a popular theory that observed abundance anomalies are due to ``internal pollution'' from intermediate mass asymptotic giant branch…
There is compelling observational evidence that globular clusters (GCs) are quite complex objects. A growing body of photometric results indicate that the evolutionary sequences are not simply isochrones in the observational plane -as…
There is vast evidence from observations of multiple stellar populations (MPs) in globular clusters (GCs). To explore the issue theoretically, this work considers two subsolar metallicities, two ages, and two initial abundance patterns: a…
Hydrogen-burning is the root cause of the star-to-star abundance variations of light nuclei in Galactic globular clusters (GC). In the present work we constrain the physical conditions that gave rise to the observed abundance patterns of…