We study for the first time the environment of massive black hole (BH) seeds (˜104-5 M⊙) formed via the direct collapse of pristine gas clouds in massive haloes (≥107 M⊙) at z > 6. Our model is based on the evolution of dark matter haloes within a cosmological N-body simulation, combined with prescriptions for the formation of BH along with both

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We explore the potential of Gaia for the field of benchmark ultracool/brown dwarf companions, and present the results of an initial search for metal-rich/metal-poor systems. A simulated population of resolved ultracool dwarf companions to Gaia primary stars is generated and assessed. Of the order of ˜24 000 companions should be identifiable outside

We compare recent precise/reliable nebular abundances - as derived from high-quality optical spectra and the most recent ICFs - in a sample of Galactic planetary nebulae (PNe) with nucleosynthesis predictions (HeCNOCl) from asymptotic giant branch (AGB) ATON models in the metallicity range Z ⊙/4 < Z < 2Z ⊙. According to the infrared dust features

We claim that the discrepancy found between the theoretical predictions for the cosmic mass function and those found in numerical simulations is due to the fact that in deriving the former, all mass elements are assumed to be at the center of the object they belong to (the all-mass-at-center problem). By an appropriate treatment of this problem

A low dispersion objective-prism survey for low-redshift emission-line galaxies (ELGs) is being carried out by the University Complutense de Madrid with the Schmidt telescope at the German-Spanish Observatory of Calar Alto (Almeria, Spain). A 4deg full aperture prism, which provides a dispersion of 1950A/mm, and IIIa-F emulsion combination has been