Related papers: NGC 6397: The metallicity trend along the isochron…
The distributions of a galaxy's gas and stars in chemical space encodes a tremendous amount of information about that galaxy's physical properties and assembly history. However, present methods for extracting information from chemical…
We derive abundance ratios for nine stars in the relatively high-metallicity bulge globular cluster NGC 6380. We find a mean cluster metallicity between [Fe/H]$= -0.80$ and $-0.73$, with no clear evidence for a variation in iron abundances…
The Hipparcos mission has made it possible to constrain the positions of nearby field stars in the colour-magnitude diagram with very high accuracy. These positions can be compared with the predictions of stellar evolutionary calculations…
We present the abundance analysis for a sample of 7 red giant branch stars in the metal-poor globular cluster NGC 4372 based on UVES spectra acquired as part of the Gaia-ESO Survey. This is the first extensive study of this cluster from…
A spectroscopic analysis of stellar spectra can be carried out using different approaches; different methods, line lists, atomic parameters, solar abundances etc. The resulting atmospheric parameters from these choices can vary beyond…
We discuss the importance of pure hydrogen white dwarf atmosphere models with Ly-$\rm \alpha$ far red wing opacity in the analysis of the white dwarf cooling sequence of the globular cluster NGC 6397. Our recently improved atmosphere models…
Spectrophotometric indices for $18$ Galactic globular clusters, obtained from CCD observations and careful reductions, were used to determine reliable calibrations on metallicity $[Fe/H]$. The indices were measured in the bandpasses adopted…
We present a HST study of the metal-rich globular cluster NGC6553 using WFPC2, NICMOS and STIS. Our primary motivation is to calibrate the STIS broad-band LP magnitude against $V_{555}$ and $I_{814}$ magnitudes for stars of known…
We used three sets of high-resolution spectra acquired with the multifiber facility FLAMES at the Very Large Telescope of the European Southern Observatory to investigate the chemical and kinematical properties of a sample of 42 horizontal…
Context. The benchmark open cluster M67 is known to have solar metallicity and similar age as the Sun. It thus provides us a great opportunity to study the properties of solar twins, as well as the evolution of Sun-like stars. Aims.…
The behaviour of the Delta nu =2 CO bands around 2.3 micron was examined by comparing observed and synthetic spectra in stars in globular clusters of different metallicity. Changes in the 12C/13C isotopic ratio and the carbon abundances…
Among stars in Galactic globular clusters the carbon abundance tends to decrease with increasing luminosity on the upper red giant branch, particularly within the lowest metallicity clusters. While such a phenomena is not predicted by…
We further study the unusual trend we found at statistically significant levels in some globular clusters, including NGC 3201: a decreasing iron abundance in red giants towards the cluster centers. We first show that recently published new…
We have observed four red clump stars in the very old and metal-rich open cluster NGC 6791 to derive its metallicity, using the high resolution spectrograph SARG mounted on the TNG. Using a spectrum synthesis technique we obtain an average…
We have used the ACS camera on HST to obtain (V,I) photometry for 5300 red-giant stars in the halo of the dominant Leo-group member NGC 3379, a galaxy usually regarded as a classic normal giant elliptical. We use this sample of stars to…
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…
Despite the advances provided by large-scale photometric surveys, stellar features - such as metallicity - generally remain limited to spectroscopic observations often of bright, nearby low-extinction stars. To rectify this, we present a…
In this paper, we revisit the data for the galaxy cluster ZwCl 0024.0+1652 provided by the GLACE survey and study the mass--metallicity function and its relationship with the environment. Here we describe an alternative way to reduce the…
We present radial velocities and chemical abundance ratios of [Fe/H], [O/Fe], [Si/Fe], and [Ca/Fe] for 264 red giant branch (RGB) stars in three Galactic bulge off-axis fields located near (l,b)=(-5.5,-7), (-4,-9), and (+8.5,+9). The…
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…