Marco Limongi

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Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with proposal GO-8679 Hubble Fellow, Department of Astronomy, University of California Los(More)
The abundance of the neutron-rich magnesium isotopes observed in metal-poor stars is explained quantitatively with a chemical evolution model of the local Galaxy that considers for the first time the metallicity-dependent contribution from intermediate mass stars. Previous models that simulate the variation of Mg isotopic ratios with metallicity in the(More)
We present the white dwarf sequence of the globular cluster M4, based on a 123 orbit Hubble Space Telescope exposure, with limiting magnitude V∼ 30, I∼ 28. The white dwarf luminosity function rises sharply for I> 25.5, consistent with the behaviour expected for a burst population. The white dwarfs of M4 extend to approximately 2.5 magnitudes fainter than(More)
We present a detailed comparison between an extended set of elemental abundances observed in some of the most metal poor stars presently known and the ejecta produced by a generation of primordial core collapse supernovae. At variance with most of the analysis performed up to now (in which mainly the global trends with the overall metallicity are(More)
We review the main properties of solar metallicity massive stars in the range 11-120 M⊙. The influence of the mass loss on the hydrostatic burning stages as well as the final explosion is discussed in some detail. We find that the minimum masses that enter the WNL, WNE and WC stages are 30 M⊙, 35 M⊙ and 40 M⊙ respectively; the limiting mass between stars(More)
We show that the ”puzzling” chemical composition observed in the extremely metal poor star HE0107-5240 may be naturally explained by the concurrent pollution of at least two supernovae. In the simplest possible model a supernova of quite low mass (∼ 15 M⊙), underwent a ”normal” explosion and ejected ∼ 0.06 M⊙ of Ni while a second one was massive enough (∼(More)
We establish an extragalactic, zero-motion frame of reference within the deepest optical image of a globular star cluster, a Hubble Space Telescope (HST) 123-orbit exposure of M4 (GO 8679, cycle 9). The line of sight beyond M4 (l, b = 351, 16) intersects the inner halo (spheroid) of our Galaxy at a tangent-point distance of 7.6 kpc (for R◦ = 8 kpc). The(More)
Motivated by the recent detection of metals in different components of the high redshift universe and by the abundance ratios measured in the extremely metal-poor stars of our Galaxy, we study the nucleosynthesis constraints that this imposes on an early generation of stars (Population III). To do so we take into account the chemical yields obtained from(More)