We report the detection of a radial velocity companion to SDSS J091709.55+463821.8, the lowest mass white dwarf currently known, with M~0.17 Msolar. The radial velocity of the white dwarf shows variations with a semi-amplitude of 148.8+/-6.9 km s-1 and a period of 7.5936+/-0.0024 hr, which implies a companion mass of M>=0.28 Msolar. The lack of

Nuclear rings are characterized by their high star formation rates, and are believed to be the products of gas inflow towards the inner regions of spiral galaxies. We present first results from a statistical survey of these rings, aimed to provide an insight into their triggering mechanisms and star formation properties. We gathered photometric

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The cosmic star formation rate is observed to drop sharply after redshift z= 2. We use two large, cosmological, smoothed particle hydrodynamics simulations to investigate how this decline is related to the evolution of gas accretion and to outflows driven by active galactic nuclei (AGN). We find that the drop in the star formation rate follows a

HARMONI is the E-ELT's first light visible and near-infrared integral field spectrograph. It will provide four different spatial scales, ranging from coarse spaxels of 60 × 30 mas best suited for seeing limited observations, to 4 mas spaxels that Nyquist sample the diffraction limited point spread function of the E-ELT at near-infrared wavelengths

The new observational O/Fe vs Fe/H relationship in halo dwarfs is analyzed in terms of a model of chemical evolution for the solar neighborhood. The role of nucleosynthesis prescriptions for SN II and SN I (both Ia and Ib) is analyzed. It is shown that, by adopting iron yields for SN II according to the observations of SN 1987A and by assuming