We have used blue near-infrared colours to select a group of 12 spectroscopically confirmed United Kingdom InfraRed Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) T dwarfs later than T4. From amongst these, we identify the first two kinematic halo T-dwarf candidates. Blue near-infrared colours have been attributed to collisionally induced

Context. Chemical abundances of light elements such as beryllium in planet-host stars allow us to study the planet formation scenarios and/or investigate possible surface pollution processes. Aims: We present here an extension of previous beryllium abundance studies. The complete sample consists of 70 stars that host planets and 30 stars without

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Aims: A recent analysis of polarization measurements of HINODE SOT/SP in the quiet Sun pointed out very complex shapes of Stokes V profiles. Here we present the first classification of the SOT/SP circular polarization measurements with the aim of highlighting exhaustively the whole variety of Stokes V shapes emerging from the quiet Sun. Methods: k

As we celebrate the International Year of Astronomy, we have been working on four different projects with the goal of making astronomy more accessible to people with special needs. These projects are 1) an astronomy book and web site for blind people, 2) an open source software for people with motor disabilities, 3) a planetarium program for the

The functional form of the galaxy-wide stellar initial mass function is of fundamental importance for understanding galaxies. So far this stellar initial mass function (IMF) has been assumed to be identical to the IMF observed directly in star clusters. But because stars form predominantly in embedded groups rather than uniformly distributed over