Observations of quasar absorption-line systems reveal that the z= 3 intergalactic medium (IGM) is polluted by heavy elements down to H I optical depths τH I≪ 10. What is not yet clear, however, is what fraction of the volume needs to be enriched by metals and whether it suffices to enrich only regions close to galaxies in order to reproduce the

EMPhaSSiS is a photometric and spectroscopic survey of the disk of the Milky Way. The survey covers 33 fields in the 3rd quadrant of the Milky Way and probes every ten degrees in Galactic Longitude between l = 180∘ - 280∘ and at Galactic Latitudes of b = -20∘, - 30∘ and - 40∘. Each field is observed in four filters, U, B, V and R, reaching depths

We present a chemical-composition analysis of 77 red-giant stars in Omega Centauri. We have measured abundances for carbon and nitrogen, and combined our results with abundances of O, Na, La, and Fe that we determined in our previous work. Our aim is to better understand the peculiar chemical-enrichment history of this cluster by studying how the

The giant radio galaxy M 87 with its proximity (16 Mpc), famous jet, and very massive black hole ((3 - 6) × 109 M &sun;) provides a unique opportunity to investigate the origin of very high energy (VHE; E > 100 GeV) γ-ray emission generated in relativistic outflows and the surroundings of supermassive black holes. M 87 has been established as a VHE

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Context. The spectral predictions of stellar population models are not as accurate in the ultra-violet (UV) as in the optical wavelength domain. One of the reasons is the lack of high-quality stellar libraries. The New Generation Stellar Library (NGSL), recently released, represents a significant step towards the improvement of this situation. Aims