Context. The Helioseismic and Magnetic Imager (HMI) provides continuum images and magnetograms with a cadence better than one per minute. It has been...

The relatively large neutral hydrogen contents and enhanced density of companion galaxies around Seyfert 2 galaxies suggests that tidal interaction could play a...

Aims. We investigate the influence of the interstellar medium (ISM) on debris discs using a statistical approach. We probe the effect of the ISM on debris disc...

Context. The dependence of the luminosity function (LF) of cluster galaxies on the evolutionary state of the parent cluster is still an open question, in...

Context. The majority of all galaxies reside in groups of fewer than 50 member galaxies. These groups are distributed in various large-scale environments from...

Context: For the first time, spectroscopic galaxy redshift surveys are enabling galaxies to be studied with the nearest quasars. This allows the dependence of...

We report the discovery of two L dwarfs (the new spectral class defined for dwarfs cooler than the M type) in a two-epoch CCD proper motion survey of 413 square...

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Context: On the nature, redshift, stellar populations and dust properties of optically faint or non-detected extremely red objects. Aims: Determining the nature...