The origin of the high X-ray luminosities of most ultraluminous X-ray sources (ULXs) still remains poorly understood. Most of the scenarios proposed to explain their nature assume that ULXs are powered by accretion on to a black hole (BH). In this case, the detection of compact radio emission and the location of the ULXs in the Fundamental Plane (X

We measure the differential microlensing of the UV Fe II and Fe III emission line blends between 14 quasar image pairs in 13 gravitational lenses. We find that the UV iron emission is strongly microlensed in four cases with amplitudes comparable to that of the continuum. Statistically modeling the magnifications, we infer a typical size of r_s\sim

From an analysis of almost 2000 Galaxy Evolution Explorer images of galaxies with morphological types ranging from E to Sab, we have found a significant subset (28 per cent) that show ultraviolet (UV) emission outside R25. We have obtained Hα imaging of 10 such galaxies, and found that their star formation rates are similar in the UV and in Hα

We present 12 yr of monitoring of the gravitational lens Q0142-100 from the Teide Observatory. The data, taken from 1999 to 2010, comprise 105 observing nights with the IAC80 Telescope. The application of the δ2 method to the dataset leads to a value for the time delay between both components of the system of 72 ± 22 days (68% confidence level)

A statistical analysis of the orientation of Nabatean sacred monuments demonstrates that astronomical orientations were often part of an elaborated plan and possibly a trace of the astral nature of the Nabataean religion. Petra and other monuments in the ancient Nabataean kingdom have proven to be marvellous laboratories for the interaction between

We report experimental oscillator strengths for 28 infrared Fe I transitions, for which no previous experimental values exist. These transitions were selected to address an urgent need for oscillator strengths of lines in the H-band (between 1.4 μm and 1.7 μm) required for the analysis of spectra obtained from the Sloan Digital Sky Survey (SDSS-III