The International Research on the Interior of the Sun (IRIS) helioseismometer measures the full disk line of sight velocity of the Sun. In fact, it makes a photometric mesurement using two monochromatic spectral windows located on the wings of the D1 solar line. This is a non-linear measurement. Before a scientific exploitation of the IRIS data

We present the results of a numerical adaptive mesh refinement hydrodynamical and N-body simulation in a Λ cold dark matter cosmology. We focus on the analysis of the main properties of massive galaxies (M* > 1011 M⊙) at z = 0. For all the massive virtual galaxies, we carry out a careful study of their one-dimensional density, luminosity, velocity

We derive a self-consistent set of atmospheric parameters and abundances of 17 elements for the red giant star Arcturus: T eff = 4286 ± 30 K, log g = 1.66 ± 0.05, and [Fe/H] = -0.52 ± 0.04. The effective temperature was determined using model atmosphere fits to the observed spectral energy distribution from the blue to the mid-infrared (0.44 to 10

We have analyzed six OB supergiants and one giant covering spectral types from O3 to B1 in the Galactic OB association Cyg OB2 by means of an updated version of FASTWIND (Santolaya-Rey et al. cite{sph97}) that includes an approximate treatment of metal line blocking and blanketing. This large coverage in spectral type allows us to derive a new

The Hipparcos mission has made it possible to constrain the positions of nearby field stars in the colour-magnitude diagram with very high accuracy. These positions can be compared with the predictions of stellar evolutionary calculations to provide information on the basic parameters of the stars: masses, radii, effective temperatures, ages, and

High-resolution spectra of a sample of all known stars more luminous than MV=+6.5 and closer than 15 parsecs are being analyzed spectroscopically in order to derive their effective temperatures and surface gravities. These spectra are taken from the database of "A Spectroscopic Survey of Stars in the Solar Neighborhood". The analysis utilizes a