We explore the application of artificial neural networks (ANNs) for the estimation of atmospheric parameters (Teff, logg, and [Fe/H]) for Galactic F- and G-type stars. The ANNs are fed with medium-resolution (Δλ~1-2 Å) non-flux-calibrated spectroscopic observations. From a sample of 279 stars with previous high-resolution determinations of

Context. Active regions are the most prominent manifestations of solar magnetic fields; their generation and dissipation are fundamental problems in solar physics. Light bridges are commonly present during sunspot decay, but a comprehensive picture of their role in the removal of the photospheric magnetic field is still lacking. Aims: We study the

Accurate astronomical distance determination is crucial for all fields in astrophysics, from Galactic to cosmological scales. Despite, or perhaps because of, significant efforts to determine accurate distances, using a wide range of methods, tracers, and techniques, an internally consistent astronomical distance framework has not yet been

We obtained multi-epoch Very Large Telescope optical spectroscopic data in 2011 and 2012 on the ultraluminous X-ray source NGC 5408 X-1. We confirm that the He II λ4686 line has a broad component with an average full width at half-maximum of v = 780 ± 64 km s-1 with a variation of ˜13 per cent during observations spanning over four years, and is

We employ the first two years of data from the near-infrared, high-resolution SDSS-III/APOGEE spectroscopic survey to investigate the distribution of metallicity and α-element abundances of stars over a large part of the Milky Way disk. Using a sample of ≈10, 000 kinematically unbiased red-clump stars with ~5% distance accuracy as tracers, the [α

In this short letter we present our new work on the coronal emission in a sample of AGN. We used the adaptive optics system NACO on the VLT to obtain high angular resolution images (˜0.15') of the coronal emission in the vicinity of the central engine.