THE active nuclei of Seyfert 1 galaxies are characterized by a small (˜0.03 pc) region of intense broad emission lines, indicative of gas moving at extremely high velocities and ionized by a non-thermal radiation field. These spectral features are usually explained by invoking the presence of a central supermassive black hole. Here we present two

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EN EL TRABAJO SE PRESENTAN, EN PRIMER LUGAR, DATOS OBSERVACIONALES DE TRES LINEAS FOTOSFERICAS SELECCIONADAS, OBTENIENDOSE VALORES DE LOS PARAMETROS DE LAS LINEAS (ESTUDIADAS SIN RESOLUCION ESPACIAL), EN DISTINTAS POSICIONES SOBRE EL DISCO SOLAR Y A LO LARGO DE SECUENCIAS TEMPORALES. LA AUTORA ENCUENTRA DIFERENCIAS SIGNIFICATIVAS ENTRE LOS

The K1V late-type dwarf α Cen B has been monitored to search for spectroscopic variability in the Ca II H chromospheric line during its rotational period. The observations were made with the Coudé Echelle Spectrograph with the 1.4 Coudé Auxiliary Telescope at ESO, with spectral resolution 80000. Variability in flux up to 29 % and profile

In the Minimal Supersymmetric Standard Model (MSSM) the existence of an upper bound on the mass of the $CP=+1$ lightest Higgs boson, equal to $m_Z$ at tree--level and $simlt 120 GeV$ after the inclusion of radiative corrections, has important phenomenological consequences for Higgs searches. A similar bound, independent of mass parameters other

We show that grazing-incidence telescopes, like those used for X-ray imaging, present negligible instrumental polarization. This property does not depend on the number of reflections the telescope employs to lead light from the entrance pupil to the focal plane. The result applies to the various mirrors of the advanced X-ray astrophysics facility