We summarize our work on structures in different stages of aggregation, and spanning a wide range in redshift. We emphasize our work on high resdhift clusters. This comprises the analysis of ~ 7 square degrees using deep images with several broad-band optical filters. We plan to complement these with near IR observations in 4 m class telescopes

Solar prominences are cool and dense plasma suspended in the million-degree solar corona. Recent observations reveal that prominences are composed of fine and highly dynamic threads aligned with the local magnetic field. We have constructed a 3D time-dependent model of a prominence combining a magnetic field structure with 1D independent

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A generalized formulation of stellar speckle interferometry (SSI) and related techniques in terms of joint spatial/spatial-frequency energy representations are proposed. It is shown how, within this formulation, techniques such as that of Knox-Thompson, or even standard SSI, appear to be particular implementations of a more general method. This

We present observations and analysis of three barred S0 galaxies which contain smooth, luminous, stellar nuclear rings within their bars. These rings, which have little or no dust and are approximately the same color as surrounding bar and bulge, are probably the old remnants of bar-driven circumnuclear starburst episodes similar to those seen in

The European Coordination Action on HELio- and ASteroseismology (HELAS) has completed its fourth and final year of initial funding by the European Commission. Set up as a network which combines solar and stellar physics communities in the important and vigorously evolving field of seismology, HELAS has been able to coordinate the efforts of