Comparison between microlensing on quasars observed and simulated makes it possible to draw conclusions about physical parameters such as source size, quasar brightness profile, mass distribution of the lens, abundance and mass of microlenses, and relative transverse velocity between source and lens. By simulating magnification maps for different

We now consider the environment of quasars in the widest possible sense, from the circumnuclear regions to very large scales of hundreds of kiloparsecs. The circumgalactic environment of nearby quasars has been widely studied since the late 1960s in an attempt to test its influence on the triggering of nuclear activity. The underlying hypothesis is

Most of the questions in this chapter deal with sources that do not show the "classical" broad emission-line spectrum that characterizes the majority of known AGNs at high and low redshift. If that majority represents a "parent population" of AGNs, is the apparent absence of broad lines a result of obscuration, orientation, or different physical

After almost one century since their definition, the origin of lenticular galaxies is still a matter of debate. Several formation processes have been proposed in order to explain the wide variety of their observational properties. These properties could indicate that the class of lenticulars is a family formed by galaxies with different formations

At present, the Kepler mission has identified 1235 candidate stars to harbor extrasolar planets. In this contribution we compare the properties of approximately 350 of these stars with those associated with planets detected by the Doppler technique. The metallicities are analyzed, among other intrinsic features, as well as the average distance to

The radical cation of the fullerene series C-60, C-70, C-76, C-78 and C-84 were generated in oleum (fuming sulphuric acid with 30% free SO3) and analyzed by electronic absorption spectroscopy. A general agreement was found between the fullerenes radical cation spectra generated in oleum and those described in the literature and produced in other