Raffaele G. Gratton

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We review the results on distances and absolute ages of galactic globular clusters (GCs) obtained after the release of the Hipparcos catalogue. Several methods aimed at the definition of the Population II local distance scale are discussed, and their results compared. We notice that while some methods yield distances to the center of the LMC (identified(More)
High dispersion spectra (R ∼ > 40, 000) for a quite large number of stars at the main sequence turn-off and at the base of the subgiant branch in NGC6397 and NGC6752 were obtained with the UVES on Kueyen (VLT UT2). The [Fe/H] values we found are −2.03±0.02±0.04 and −1.42±0.02±0.04 for NGC6397 and NGC6752 respectively, where the first error bars refer to(More)
We study the evolution of a long strip of viscous fluid on a horizontal glass substrate under partial-wetting conditions. This initial condition develops into an array of quasi-equidistant drops. The special feature of this dewetting scenario is that the pearling process, consisting of successive stages of bulge growth and pinching-off, does not occur(More)
New improved distances and absolute ages for the Galactic globular clusters NGC6397, NGC6752, and 47 Tuc are obtained using the Main Sequence Fitting Method. We derived accurate estimates of reddening and metal abundance for these three clusters using a strictly differential procedure, where the Johnson B − V and Strömgren b− y colours and UVES high(More)
We study the stability of a constant volume of fluid spreading down an incline. In contrast to the commonly considered flow characterized by constant fluid flux, in the present problem the base flow is time dependent. We present a method to carry out consistently linear stability analysis, based on simultaneously solving the time evolution of the base flow(More)
variation dES /dt of the free energy ES associated with the Highly viscous silicone oils within a wide range of volumes were interfaces (surfaces) is completely negligible with respect left to spread on smooth horizontal substrates to investigate the to the rate of gravitational energy release dEG/dt . In these effects of capillarity on viscous gravity(More)
Having shown in a recent paper that the main sequence of ω Centauri is split into two distinct branches, we now present spectroscopic results showing that the bluer sequence is less metal-poor. We have carefully combined GIRAFFE@VLT spectra of 17 stars on each side of the split into a single spectrum for each branch, with adequate S/N to show clearly that(More)
A simple light-slicing technique for the direct measurement of the free-surface shape h(x) in onedirectional transient liquid flows is studied. The method is used to determine h(x) with a precision of the order of 10(-2) mm along a line several centimeters long, allowing for height differences of some millimeters. It is useful for transient flows in(More)
We present homogeneous abundance determinations for iron and some of the elements involved in the proton-capture reactions (O, Na, Mg, Al, and Si) for 202 red giants in 17 Galactic globular clusters (GCs) from the analysis of high-resolution UVES spectra obtained with the FLAMES facility at the ESO VLT2 telescope. Our programme clusters span almost the(More)
We present the first results from the analysis of GIRAFFE spectra of more than 1200 red giants stars in 19 Galactic Globular Clusters (GCs), to study the chemical composition of second generation stars and their link with global cluster parameters. We confirm that the extension of the Na-O anticorrelation (the most striking signature of polluted, second(More)