We derive new spectral Hγ index definitions that are robust age indicators for old and relatively old stellar populations and therefore have great potential for solving the age-metallicity degeneracy of galaxy spectra. To study this feature as a function of age, metallicity, and resolution, we have used a new spectral synthesis model that predicts

The discovery of Li in the late type secondary of the black hole binary V404 Cyg has motivated considerable interest in the presence of this light element in stars orbiting compact objects in general. We report here on a search for Li in cataclysmic binaries (CVs), where a low mass star transfers mass onto a white dwarf. For this purpose, we have

We present a second-order analytical expansion of null equatorial geodesics in the Kerr metric. The equations developed are applied to the study of light transit in compact binary systems. We show that the effects arising from path bending have a significant influence on the computed time delays, even at first order of approximation in the

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I have studied the relation between the global star formation activity and the bar structure in a sample of isolated barred galaxies. The star formation activity was quantified via the ratio between the IRAS fluxes at 25 mu m and 100 mu m. Two parameters were chosen to define the bar structure: the strength of the bar and the relative projected bar

We present Chandra, XMM-Newton, and Swift observations of the quiescent neutron star in the transient low-mass X-ray binary MAXI J0556-332. Observations of the source made during outburst (with the Rossi X-ray Timing Explorer) reveal tracks in its X-ray color-color and hardness-intensity diagrams that closely resemble those of the neutron-star Z