We report two-dimensional MHD simulations which demonstrate that photospheric 5 minute oscillations can leak into the chromosphere inside small-scale vertical magnetic flux tubes. The results of our numerical experiments are compatible with those inferred from simultaneous spectropolarimetric observations of the photosphere and chromosphere

Aims:A recent catalogue by Flesch & Hardcastle presents two major anomalies in the spatial distribution of QSO candidates: i) an apparent excess of such objects near bright galaxies, and ii) an excess of very bright QSO candidates compared to random background expectations in several regions of the sky. Because anyone of these anomalies would be

Cometary outbursts are not completely understood. We have performed a continuous coverage of the recent 17P/Holmes outburst in order to learn more about the processes that generate an outburst of the 2007 magnificence.

About 150 weakly magnetic neutron stars are known to accrete matter from low-mass stars in neutron star low-mass X-ray binaries (NS-LMXBs). Accretion in these systems is not steady and as a consequence luminosity and spectral shape change on timescales from milliseconds to months. Energy spectrum and rapid variability vary in a correlated way

In this work we present the results of a systematic search for diffuse bands (DBs, hereafter) in the circumstellar envelopes of a carefully selected sample of post-AGB stars. We concentrated on analyzing 9 of the DBs most commonly found in the interstellar medium. The strength of these features is determined using high-resolution optical

We propose a systematic study of all observations of black hole and neutron star low-mass X-ray binaries (LMXBs) in the Spitzer archive. At least 125 unique LMXBs have now been observed with Spitzer, many as part of large Legacy surveys of the Galactic plane and bulge. This LMXB archive has remained largely unexplored. The proposed archival study