We present a summary of our ongoing efforts to study one of the brightest ultraluminous X-ray source, NGC 1313 X-2. Despite a large coverage in the X-rays, much of the information we have about the source and its environment comes from optical wavelengths. Here, we report on the properties of the stellar environment, and the differences in the

The large scale expansion rate of the Universe is given by the value of the Hubble constant. Several methods have been used to determine the Hubble constant: CMB anisotropies, supernovae observations, and AGN at high redshift. In this work we use the Grainge method to estimate the Hubble constant by using the Sunyaev-Zeldovich effect with data from

The bright nebular complex NGC 6334 contains some of the most active sites of massive star formation known in our Galaxy. It is located at a distance from the Sun of 1.62 kpc and has a total mass of a few 10^5~M_&sun;. The physical characteristics of the active spots range widely, from well developed expanding HII regions to deeply embedded, still

13 out of 48 nova-likes in the 2.8-4 h orbital period range are eclipsing SW Sex stars - these are all the eclipsing cataclysmic variables (CVs) in this range. Apparently, SW Sex stars are very frequent and probably represent an important stage in CV evolution, as they densely gather just above the period gap and exhibit extremely high mass

Recent Hubble Space Telescope (HST)/Advanced Camera for Surveys (ACS) observations revealed the presence of a double subgiant branch (SGB) in the core of the Galactic globular cluster NGC 1851. This peculiarity was tentatively explained by the presence of a second population with either an age difference of about 1 Gyr, or a higher C+N+O abundance

We present the first results of a ground-based program to determine the proper motion of the Magellanic Clouds (MCs) relative to background quasars (QSO), being carried out using the Iréneé du Pont 2.5 m telescope at Las Campanas Observatory, Chile. Eleven QSO fields have been targeted in the Small Magellanic Cloud (SMC) over a time base of six