In this work we present a recent study of the bar fraction in the ComaCluster galaxies based on a sample of ~190 galaxies selected from theSloan Digital Sky  Survey Data Release 6 and observed with the Hubble Space Telescope (HST)  Advanced  Camera for Survey  (ACS).The unprecedented resolution of the HST-ACS  images allows us  to explore the presence of bars, detected by visual classification, throughout luminosity range of 9 mag (-23 < Mr < -14), permitting us to study th poor known region  of dwarf galaxies. We find that  bars are hosted bygalaxies in  a tight range of both  luminosities

The Gran Telescopio CANARIAS open new prospects to characterise the oldest population of stars in our Galaxy with the discovery of a cold and distant low-metallicity star A new object with an age of thousands of millions of years and a mass of one tenth of the Sun, placing it at the frontier between low-mass stars and brown dwarfs, has been discovered as the furthest of its class in Milky Way. Nicknamed ULAS1350, this subdwarf could become on of the key element to improve our knowledge on the first steps of the formation of our Galaxy.The team of European astronomers responsible for the

A long-standing issue in solar astrophysics concerns the strength and structure variations with height of the magnetic field in the chromosphere of the quiet Sun. Our empirical knowledge on this issue has remained vague notwithstanding the qualitative information provided by high resolution monochromatic images of the solar atmosphere taken at various wavelengths across strong spectral lines like H-alpha showing a mass of cell-spanning fibrils as a flattened carpet, with upright ones jutting out from network patches. Unfortunately, such images do not provide quantitative information on the

Recent observations of the rotation curve of M31 show a rise of the outer part that cannot be understood in terms of standard dark matter models or perturbations of the galactic disk by M31?s satellites. Here, we propose an explanation of this dynamical feature based on the in?uence of the magnetic ?eld within the thin disk. We have considered standard mass models for the luminous mass distribution, a Navarro?Frenk?White model to describe the dark halo, and we have added up the contribution to the rotation curve of a magnetic ?eld in the disk, which is described by an axisymmetric pattern

We present a visual determination of the number of bright points (BPs) existing in the quiet Sun, which are structures thought to trace intense kG magnetic concentrations. The measurement is based on a 0farcs1 angular resolution G-band movie obtained with the Swedish Solar Telescope at the solar disk center. We find 0.97 BPs Mm-2, which is a factor 3 larger than any previous estimate. It corresponds to 1.2 BPs per solar granule. Depending on the details of the segmentation, the BPs cover between 0.9% and 2.2% of the solar surface. Assuming their field strength to be 1.5 kG, the detected BPs

In a recently published differential analysis (see ApJ, 724, 1536, Dec. 1 issue) , we have derived abundance corrections for iron lines, using synthetic spectra from solar magnetoconvection simulations that were performed via running the Copenhagen stagger-code on massively-parallel clusters. The series of 3D snapshots used for the spectral synthesis covers 2.5 solar hours in the statistically stationary regime of the convection.Crucially, we show that the effect of magnetic fields on solar abundancedeterminations can not be neglected. This is equally valid for all three different Fe