Large telescopes require a very precise calibration in order to maximize its scientific output. Current catalogues of standard stars are generally too bright for 10m telescopes. For GTC we are planning to produce a catalogue with calibration stars which are suitable for this telescope. In this paper we describe the first steps of the GTC

After revisiting the hierarchy problem of the Standard Model and its implications for the scale of New Physics, I consider the finetuning problem in two main scenarios beyond the Standard Model: Supersymmetry (both in the Minimal Supersymmetric Standard Model and alternative models) and Little Higgs models. The main conclusions are that New Physics

We present preliminary results on the analysis of very deep echelle UVES (8m VLT) spectra of the Galactic H II region S311 (NGC 2467) located outside the Solar circle. The data cover from 3100 to 10450 Å with a resolution R ~ 8800. We have detected and measured more than 300 emission lines, some of them are faint recombination lines of heavy

Novel spectropolarimetric observations of the He I multiplet are used to explore the dynamics of the chromospheric oscillation above sunspot umbrae. The results presented here provide strong evidence in support of the two-component model proposed by Socas-Navarro and coauthors. According to this model, the waves propagate only inside channels of

The analysis of the Hanle effect in solar molecular lines allows us to obtain empirical information on hidden, mixed-polarity magnetic fields at subresolution scales in the (granular) upflowing regions of the ``quiet'' solar photosphere. Here we report that collisions seem to be very efficient in depolarizing the rotational levels of MgH lines

Esta tesis presenta un análisis conjunto de los espectros ultravioleta, óptico e infrarrojo cercano de las estrellas Vega y Porción. Para los análisis se hace uso de modelos de atmósfera planoparalelos, en equilibrio termodinámico local, con el llamado efecto de line-blanketing y la aproximación de la longitud de mezcla para la convección, y