En esta Tesis Doctoral, tras una introducción sobre las estructuras magnéticas solares, en particular aquéllas no resueltas espacialmente, sus observaciones y técnicas de diagnóstico, y el problema del transporte de radiación polarizada en presencia de campo magnético, se presenta un nuevo código de inversión de la ecuación de transporte radiativo

IAUC 6902 available at Central Bureau for Astronomical Telegrams.

We report on the results of optical follow-up observations of the counterpart of GRB970508 between 7 hours and 100 days after the event. Multi-colour U, B, V, Rc and Ic band observations were obtained during the first three consecutive nights. The Rc light curve rises to a maximum 1.8 days after the burst and after this declines with a power law

Mean-field theory in its kinematic form with the quasi-linear approximation is widely used for the modelling of the transport of weak magnetic fields in turbulent media. The validity of this approach to real astrophysical flows is discussed. Numerically evaluating the turbulent electromotive force using Lagrangian analysis for a set of simple

Using the Nordic Optical Telescope, La Palma, Spain, optical studies of OT/GRB970508 were initiated 3 hours 5 minutes after the high energy event (This appears to be sooner than achieved elsewhere, for any optical transient). The OT was clearly detected in the earliest images. The last observation was done August 13-15, i.e. 95-97 days after the

We present new near-infrared images and spectra of the circumnuclear star formation regions in M100. Images in J, H, and K have been obtained in conditions of 0.3'' seeing using IRCAM3 on UKIRT, and show a host of objects not apparent in previous images (cf. Knapen et al. 1995, ApJ, 443, L73). We have also obtained H- and K-band spectra with CGS4