We report the discovery of two new field variable stars based on CCD observations carried out between October and December, 2000. Using multicolour photometry we could classify these stars as W UMa type variables, and we could determine accurate period for each of them.

Standard cosmology predicts that dwarfs were the first galaxies to be formed in the universe and that many of them merge afterward to form bigger galaxies such as the Milky Way. This process would have left behind traces such as tidal debris or star streams in the outer halo. We report here the detection of a very low density stellar system at 50+/

The discovery of a system of Herbig-Haro objects ejected by young, low mass stars in the &sigma Orionis region (Reipurth et al. 1998) has given rise to models of the photoionization of a neutral jet by an external source. We present long-slit spectra of high spectral resolution of HH 444 and numerical simulations for this Herbig-Haro object using `

We study the generation of vorticity in the magnetic boundary layer of buoyant magnetic tubes and its consequences for the trajectory of magnetic structures rising in the solar convection zone. When the Reynolds number is well above 1, the wake trailing the tube sheds vortex rolls, producing a von Kármán vortex street, similar to the case of flows

As part of an ongoing project aimed at studying the age and metallicity gradients of the stellar populations along the bars of a sample of barred spirals of different morphological types, we present our first results on NGC 4314 (SBa). We have obtained optical and NIR colours and spectral indices along the bar and we interpret some of these results

Dwarf galaxies may play a key role in the formation and evolution of bigger systems. This makes it a topic of major interest to know how they form and evolve and, in particular, how their star formation histories (SFHs) have proceeded since their birth. For nearby galaxies, the colour-magnitude diagram (CMD) contains stars formed over their full