We present a deep I, Z photometric survey (I compl = 22 mag) covering a total area of 1.12 deg2 in the σ Orionis cluster. Using I, I - Z color-magnitude diagrams, we have selected 165 photometric candidates (I = 16-24 mag), which correspond to a mass interval from 0.11 down to 0.006 M &sun;. Using J-band photometry, we have found that 120 of 147

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We have started a project to search for symbiotic stars using the data from IPHAS, the Hα survey of the Northern Galactic plane. Candidates are selected from the IPHAS photometric catalogue based on their colors, combined with the information in the near-infrared from 2MASS. So far, follow-up spectroscopy allowed us to discover 14 new symbiotic

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How will quasar studies be pursued in the near future? Starting from a summary of past achievement, we ask questions on expected instrumental and computational advancements that can shape quasar research in a foreseeable way. There is excitement due to the planned large new-generation telescopes, ground-based and in space. New surveys will lead to

Considering Galaxy spectra as multidimensional vectors, we use the k-means algorithm and the minimum spanning tree to show that the data in the Sloan Digital Sky Survey do not fill the entire space but are confined to a manifold with very low dimensionality. More precisely, all the spectra can be described in terms of only two degrees of freedom