Related papers: Metallicity variations in the Type II globular clu…

We present elemental abundances for 855 red giant branch (RGB) stars in the globular cluster Omega Centauri (w Cen) from spectra obtained with the Blanco 4m telescope and Hydra multifiber spectrograph. The sample includes nearly all RGB…

Low resolution spectra have been used to measure individual metal abundances of RR Lyrae stars in NGC 6441, a Galactic globular cluster known to have very unusual horizontal branch morphology and periods of the RR Lyrae stars for its high…

NGC 2420 is a $\sim$2 Gyr-old well-populated open cluster that lies about 2 kpc beyond the solar circle, in the general direction of the Galactic anti-center. Most previous abundance studies have found this cluster to be mildly metal-poor,…

Globular cluster (GC) stars composed of pristine material (first-generation, 1G, stars) are not chemically homogeneous, as they exhibit extended sequences in the "Chromosome Map" (ChM). Recent studies characterized 1G stars within the…

The FLAMES survey ``Na-O anti-correlation and HB" uncovered the modern standard for globular clusters (GCs), that is their ubiquitous multiple stellar populations (MPs) distinct by the abundance of proton-capture elements. That survey can…

The globular cluster NGC 288 was previously reported to exhibit two distinct red giant branches (RGBs) in the narrow-band Calcium (HK) and Str\"omgren b and y band passes. In order to investigate this phenomenon further, we obtained…

The stellar populations in a stellar complex in NGC 6946 are analyzed on images taken with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. The complex is peculiar by its very high density of stars and clusters and…

We report on evidence of the inhomogeneity (multiplicity) of the stellar population in the Galactic globular cluster (GC) NGC 3201, which is irregularly reddened across its face. We carried out a more detailed and careful analysis of our…

The galactic magnetic chemically peculiar (mCP) stars of the upper main sequence are well known as periodic spectral and light variables. The observed variability is obviously caused by the uneven distribution of overabundant chemical…

By using the multifiber spectrograph FLAMES mounted at the ESO-VLT, we have obtained high-resolution spectra for 18 giant stars, belonging to 3 old globular clusters of the Large Magellanic Cloud (namely NGC 1786, 2210 and 2257). While…

It is unclear whether chemically peculiar stars of the upper main sequence represent a class completely distinct from normal A-type stars, or whether there exists a continuous transition from the normal to the most peculiar late F- to early…

The optical colors of globular clusters (GCs) in most large early-type galaxies are bimodal. Blue and red GCs show a sharp difference in the radial profile of their surface number density in the sense that red GCs are more centrally…

We present the first detailed chemical abundance study of the ultra-faint dwarf galaxy Tucana II based on high-resolution Magellan/MIKE spectra of four red giant stars. The metallicity of these stars ranges from [Fe/H] = -3.2 to -2.6, and…

A combined effort utilizing spectroscopy and photometry has revealed the existence of a new globular cluster class. These "anomalous" clusters, which we refer to as "iron-complex" clusters, are differentiated from normal clusters by…

The globular cluster HP~1 is projected at only 3.33 degrees from the Galactic center. Together with its distance, this makes it one of the most central globular clusters in the Milky Way. It has a blue horizontal branch (BHB) and a…

Galactic globular clusters (GCs) are known to host multiple stellar populations: a first generation with a chemical pattern typical of halo field stars and a second generation (SG) enriched in Na and Al and depleted in O and Mg. Both…

Long-slit medium-resolution spectra of the Galactic globular clusters (GCs) NGC6229 and NGC6779, obtained with the CARELEC spectrograph at the 1.93-m telescope of the Haute-Provence observatory, have been used to determine the age, helium…

We report new chemical abundances of 23 bright red giants of the globular cluster M3, based on high-resolution spectra obtained with the Keck I telescope. Combining these data with a previously-reported small sample of M3 giants obtained…

A recent analysis comparing the [Na/Fe] distributions of red giant branch (RGB) and asymptotic giant branch (AGB) stars in the Galactic globular cluster NGC 6752 found that the ratio of Na-poor to Na-rich stars changes from 30:70 on the RGB…

Globular clusters display significant variations in their light-element content, pointing to the existence of a second stellar generation formed from the ejecta of an earlier generation. The nature of these internal polluters is still a…