The influence of microlensing on the profiles of emission lines generated in a biconical geometry is discussed. Microlensing amplification in this anisotropic model is not directly related to the bicone's intrinsic size but, rather, depends on the orientation of the bicone axis and on the cone aperture. The orientation of the projected bicone with

En este trabajo hemos estudiado la luz difusa en cúmulos y grupos de galaxias. La luz difusa está compuesta por estrellas desligadas de las galaxias del cúmulo y que se mueven bajo la acción del potencial global del cúmulo. Esta componente cúmular corresponde a un 5-15% de la masa total del cúmulo. Fue descubierta por primera vez en el cúmulo de

As part of a major program to use isolated Local Group dwarf galaxies as near-field probes of cosmology, we have obtained deep images of the dwarf irregular galaxy Leo A with the Advanced Camera for Surveys aboard the Hubble Space Telescope. From these images we have constructed a color-magnitude diagram (CMD) reaching apparent [absolute]

Aims:We investigate the dynamics of the nebula around the symbiotic star Hen 2-147, determine its expansion parallax, and compare it with the distance obtained via the period-luminosity relation for its Mira variable. Methods: A combination of multi-epoch HST images and VLT integral field high-resolution spectroscopy is used to study the nebular

In the framework of a long-term program aimed at studying stellar populations in the Carina dSph galaxy, we present the photometric calibration of the two mosaic cameras adopted in this experiment, the MOSAICII CCD camera available at the 4-m CTIO Blanco telescope, and the WFI available at the 2.2-m ESO/MPI telescope. We discuss the data reduction

An accurate and traceable photometric calibration is becoming increasingly important for large telescopes if they are to reach their full potential. The scientific community of the Gran Telescopio Canarias (GTC) has recognized this and there are programmes underway to ensure that suitable calibration standards are in place. The aim is to extend the