We present results for the spectral distortions of the cosmic microwave background (CMB) arising due to bound-bound transitions during the epoch of cosmological hydrogen recombination at frequencies down to ν ~100MHz. We extend our previous treatment of the recombination problem now including the main collisional processes and following the

Using integral-field spectroscopy, the SAURON survey has shown that early-type galaxies, once thought to be essentially devoid of gas, commonly show ionised gas emission. This emission is found with a rich variety of distributions and kinematics, ranging from very uniform disks or rings, and large-scale twisted structures, to flocculent and

We detected tertiary components of close binaries from spectroscopy and light curve modelling, investigated the light-travel time effect and the possibility of magnetic activity cycles, measured mass ratios for unstudied systems, and derived absolute parameters. We carried out new photometric and spectroscopic observations of five bright close

Observations show that galaxies follow a mass-metallicity relation over a wide range of masses. One currently favoured explanation is that less massive galaxies are less able to retain the gas and stellar ejecta and thus may lose the freshly produced metals in the form of galactic outflows. Galaxies with a low current star formation rate have been

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Context: To investigate the formation of sub-stellar objects, we observed a sample of ultracool dwarf members of the Upper Scorpius OB association. Aims: The properties of disks, such as their composition, life-time, and frequency compared to the accretor frequency, provide important clues to the mechanisms responsible for the formation of stellar