Context. Solar magnetic fields are regularly extrapolated into the corona starting from photospheric magnetic measurements that can be affected by significant uncertainty. Aims: We study how inaccuracies introduced into the maps of the photospheric magnetic vector by the inversion of ideal and noisy Stokes parameters influence the extrapolation of

We have carried out high-precision photometry on a large number of archival Hubble Space Telescope images of the Galactic globular cluster NGC 6752, to search for signs of multiple stellar populations. We find a broadened main sequence (MS) and demonstrate that this broadening cannot be attributed either to binaries or to photometric errors. There

Context. The EUROpean Near Earth Asteroid Research (EURONEAR) is a network which envisions to bring some European contributions into the general context traced by the Spaceguard Foundation which was carried out during the last 15 years mainly by the US with some modest European and amateur contributions. Aims: The number of known near Earth

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Low mass X-ray binaries that have independent distance measurements and show thermonuclear X-ray bursts are ideal sources for constraining the equation of state of neutron star matter. I will introduce our program to systematically measure the distances, masses, and radii of neutron stars in such binaries. We utilize high energy resolution X-ray

Aims: We investigate the temporal evolution of magnetic flux emerging within a granule in the quiet-Sun internetwork at disk center. Methods: We combined IR spectropolarimetry of high angular resolution performed in two Fe i lines at 1565 nm with speckle-reconstructed G-band imaging. We determined the magnetic field parameters by a LTE inversion of