New observations and derived chemical abundances are reported for a sample of 57 bulge planetary nebulae (PN). Together with our previous results, a total of over a hundred objects have been analyzed, which constitute one of the largest samples of bulge nebulae studied under homogeneous conditions, including equipment and reduction procedures. In general, our data show a good agreement with som...

We analyse the effects on the predictions for the microlensing searches toward the Galactic bulge coming from the fact that not all the stars monitored belong to the bulge itself, but that a non–negligible fraction of them actually are in the Galactic disk. The different distribution and motions of these disk stars make their associated microlensing rates and event duration distributions to be ...

The bulge is a region of the Galaxy of tremendous interest for understanding galaxy formation. However measuring photometry and kinematics in it raises several inherent issues, such as severe crowding and high extinction in the visible. Using the Besançon Galaxy model and a 3D extinction map, we estimate the stellar density as a function of longitude, latitude and apparent magnitude and we dedu...

We use semi-analytical modelling techniques to investigate the progenitor morphologies of present day ellipticals. We find that, independent of the environment , the fraction of mergers of bulge dominated galaxies (early-types) increases with time. The last major merger of bright present day ellipticals with M B −21 is preferentially between bulge dominated galaxies, while those with M B ∼ −20 ...

Aggressive early deflation is a QR algorithm deflation strategy that takes advantage of matrix perturbations outside of the subdiagonal entries of the Hessenberg QR iterate. It identifies and deflates converged eigenvalues long before the classic small-subdiagonal strategy would. The new deflation strategy enhances the performance of conventional large-bulge multishift QR algorithms, but it is ...

We use a Monte Carlo technique together with a simple model for the distribution of dust in M31 to investigate the observability and spatial distribution of classical novae in M31. By comparing our model positions of novae to the observed positions, we conclude that most M31 novae come from the disk population, rather than from the bulge population as has been thought. Our results indicate that...

We provide a set of microlensing optical depth maps for M31. Optical depths towards Andromeda were calculated on the basis of a four component model of the lens and source populations: disk and bulge sources lensed by bulge, M31 halo and Galactic halo lenses. We confirm the high optical depth and the strong optical depth gradient along the M31 minor axis due to a dark halo of lenses and also di...