We obtained linear polarization observations of 82 A/B-type stars in the young cluster NGC 6611, in order to probe the circumstellar material and to search for any evidence of intracluster or interstellar material that could also contribute to the polarization. We found linear polarization values that reach up to 14%. We consider the distribution

We investigate the dynamics of and the relations between small-scale penumbral and photospheric features near the outer penumbral boundary: penumbral grains (PGs), dark penumbral fibrils, granules, and photospheric G-band bright points. The analysis is based on a 2 h time sequence of a sunspot close to disc center, taken simultaneously in the G

Sunspot penumbrae exhibit prominent fine structure. Different interpretations of spectropolarimetric observations suggest different, sometimes contradictory, properties of this fine structure. In this paper we show that the results of inversions of penumbral infrared profiles based on one-component models with gradients of the atmospheric

Here we report on the first observational investigation of the Zeeman effect in the G band around 4305 Å. Our spectropolarimetric observations of sunspots with the Zürich Imaging Polarimeter at the Istituto Ricerche Solari Locarno confirm our previous theoretical prediction that the molecular Zeeman effect produces measurable circular polarization

Analysis of archival data from the BeppoSAX Wide Field Cameras has yielded further detections of superbursts. Remarkably, several are from a persistent low-mass X-ray binary (LMXB) that radiates within a few tens of percent of the Eddington limit, in contrast to all other superbursts detected with BeppoSAX and RXTE which are from LMXBs radiating

We report simultaneous X-ray, optical, and radio observations of V404 Cyg in quiescence. The X-ray flux varied dramatically by a factor of >20 during a 60 ks observation. X-ray variations were well correlated with those in Hα , although the latter include an approximately constant component as well. Correlations can also be seen with the optical