We study the dependence of the number density and properties of quasars on the background galaxy density using the currently largest spectroscopic data sets of quasars and galaxies. We construct a galaxy number density field smoothed over the variable smoothing scale of between approximately 10 and 20 h ‑1 Mpc over the redshift range 0.46 z 0.59

We study the quiet Sun magnetic fields using spectropolarimetric observations of the infrared and visible Fe I lines at 6301.5, 6302.5, 15648, and 15653 Å. Magnetic field strengths and filling factors are inferred by the simultaneous fit of the observed Stokes profiles under the MISMA hypothesis. The observations cover an intranetwork region at the

Context. Open clusters are ideal test particles for studying the formation and evolution of the Galactic disk. However, the number of clusters with information about their radial velocities and chemical compositions remains largely insufficient. Aims: We attempt to increase the number of open clusters with determinations of radial velocities and

Radial velocity studies have provided the majority of all exoplanet discoveries. Using the radial velocity techniques on young stars suffers from problems with magnetic activity jitter, which has been studied for years, and the effects of circumstellar disks, which has remained unstudied. Here we study the disk-embedded star BP Psc using high

We present Very Large Array (VLA) radio continuum and Infrared Astronomy Satellite (IRAS) far-infrared (FIR) observations of 16 low luminosity galaxies of mostly low surface brightness. All galaxies had previously claimed single dish radio continuum detections. However, at the frequencies of our observations (1.49 and 8.48 GHz), we find significant

Accurate calibration of data is essential for the current generation of cosmic microwave background (CMB) experiments. Using data from the Very Small Array (VSA), we describe procedures which will lead to an accuracy of 1 per cent or better for experiments such as the VSA and CBI. Particular attention is paid to the stability of the receiver