El objetivo de la tesis es el estudio de las estrellas calientes de rama horizontal en cúmulos globulares. Estas estrellas aclanzan hasta 35000 k de temperatura y puede ser las responsables del escexo UV en galaxias elípticas. Se ha utilizado UVES+VLT para estudiar la velocidad de rotación de 61 estrellas en diferentes cúmulos utilizando

NAOMI (Nasmyth Adaptive Optics for Multi-purpose Instrumentation) is a recently completed and commissioned astronomical facility on the 4.2m William Herschel Telescope. The system is designed to work initially with Natural Guide Stars and also to be upgradeable for use with a single laser guide star. It has been designed to work with both near

The Instituto de Astrofísica de Canarias (IAC), Spain, together with the Spanish company Tecdis Displays Ibérica, S.A., are developing voltage tunable optical retarders using liquid crystals as phase retarding medium. The ROCLIs are built for being used in the Imaging Magnetograph eXperiment (IMaX), which is one of the instruments aboard of the

The description of the Imaging Magnetograph eXperiment (IMaX) is presented in this contribution. This is a magnetograph which will fly by the end of 2006 on a stratospheric balloon, together with other instruments (to be described elsewhere). Especial emphasis is put on the scientific requirements to obtain diffraction-limited visible magnetograms

IAUC 8072 available at Central Bureau for Astronomical Telegrams.

We present an overview of the spectral variability of the peculiar F-type hypergiant ρ Cas, obtained from our long-term monitoring campaigns over the past 8.5 yr with four spectrographs in the northern hemisphere. Between 2000 June and September an exceptional variability phase occurred when the V brightness dimmed by about a full magnitude. The