This paper presents an overview of the radiative transfer problem of calculating the spectral line intensity and polarization that emerges from a (generally magnetized) astrophysical plasma composed of atoms and molecules whose excitation state is significantly influenced by radiative transitions produced by an anisotropic radiation field. The

We have analyzed ACS/WFC and WFPC2 images from HST, as well as ground-based data to study the radial distribution of the double sub-giant branch (SGB) recently discovered in the Galactic globular cluster NGC 1851. We found that the SGB split can be followed all the way from the cluster center out to at least 8´ from the center. Beyond this distance

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We analyse a high-resolution, fully cosmological, hydrodynamical disc galaxy simulation, to study the source of the double-exponential light profiles seen in many stellar discs, and the effects of stellar radial migration upon the spatiotemporal evolution of both the disc age and metallicity distributions. We find a `break' in the pure exponential

We study the response of the low-degree, solar p-mode frequencies to the unusually extended minimum of solar surface activity since 2007. A total of 4768 days of observations collected by the space-based, Sun-as-a-star helioseismic GOLF instrument are analyzed. A multi-step iterative maximum-likelihood fitting method is applied to subseries of 365

We present subarcsecond resolution mid-infrared (mid-IR) photometry in the wavelength range from 8 to 20 μm of 18 Seyfert galaxies, reporting high spatial resolution nuclear fluxes for the entire sample. We construct spectral energy distributions (SEDs) that the active galactic nucleus (AGN) dominates, relatively uncontaminated by starlight, adding