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We put limits on the time variation of the electron mass in the early universe using observational primordial abundances of D, 4He, and 7Li, recent data from the cosmic microwave background, and the 2dFGRS power spectrum. Furthermore, we use these constraints together with other astronomical and geophysical bounds from the late universe to test the

We study the color structure of disk galaxies in the Groth strip at redshifts 0.1 z 1.2. Our aim is to test formation models in which bulges form before/after the disk. We find smooth color distributions with gentle outward blueing across the galaxy image: bulges are not distinctly redder than their disks; and bulge colors strongly correlate with

The ESO Very Large Telescope Interferometer (VLTI) offers access to the four 8 m Unit Telescopes (UT) and the four 1.8 m Auxiliary Telescopes (AT) of the Paranal Observatory located in the Atacama Desert in northern Chile. The fourth AT has been delivered to operation in December 2006, increasing the flexibility and simultaneous baselines access of

NGC 1313 X-2 is one of the brightest ultraluminous X-ray sources in the sky, at both X-ray and optical wavelengths; therefore, quite a few studies of available ESO VLT and HST data have appeared in the literature. Here, we present our analysis of VLT/FORS1 and HST/ACS photometric data, confirming the identification of the B ~ 23 mag blue optical

We present VLT FLAMES spectroscopic observations (R~6500) in the Ca II triplet region for 470 probable kinematic members of the Sculptor (Scl) dwarf spheroidal galaxy. The accurate velocities (+/-2 km s-1) and large area coverage of Scl allow us to measure a velocity gradient of 7.6+3.0-2.2 km s-1 deg-1 along the projected major axis of Scl, likely