Magnetic field vector ambiguity resolution in a quiescent prominence observed on two consecutive days

Context. Magnetic field vector measurements are always ambiguous, that is, two or more field vectors are solutions of the observed polarisation. Aims. The aim of the present paper is to solve the ambiguity by comparing the ambiguous field vectors obtained in the same prominence observed on two consecutive days. The effect of the solar rotation is to modify the scattering angle of the prominence radiation, which modifies the symmetry of the ambiguous solutions. This method, which is a kind of tomography, was successfully applied in the past to the average magnetic field vector of 20 prominences observed at the Pic du Midi. The aim of the present paper is to apply this method to a prominence observed with spatial resolution at the THÉMIS telescope (European site at Izaña, Tenerife Island). Methods. The magnetic field vector is measured by interpretation of the Hanle effect observed in the He I D3 5875.6 Å line, within the horizontal field vector hypothesis for simplicity. The ambiguity is first solved by comparing the two pairs of solutions obtained for a “big pixel” determined by averaging the observed Stokes parameters in a large region at the prominence centre. Each pixel is then disambiguated by selecting the closest solution in a propagation from the prominence centre to the prominence boundary. Results. The results previously obtained on averaged prominences are all recovered. The polarity is found to be inverse with a small angle of about −21° between the magnetic field vector and the long axis of the filament. The magnetic field strength of about 6 G is found to slightly increase with height, as previously observed. The new result is the observed decrease with height, of the absolute value of the angle between the magnetic field vector and the long axis of the filament. Conclusions. This result is in excellent agreement with prominence magnetohydrodynamical models.

New record of Geissleria declivis (Hust.) Lange-Bert. (Bacillariophyceae) in Europe, the first in Poland

As a result of the research carried out in Lakes Duszatyńskie and the Olchowaty stream, a new European site with Geissleria declivis (Hust.) Lange-Bert. was found — a new species for Poland. The highest abundance of G. declivis has been observed on sandy substrate and small stones in the littoral zone of the Upper Lake during the spring season. The species occurred together with Achnanthidium minutissimum (Kütz.) Czarn. var. minutissimum, A. catenatum (Bily & Marvan), Fragilaria leptostauron (Ehrenb.) Hust. var. leptostauron and F. pinnata Ehrenb. var. pinnata. Our observations revealed that G. declivis develops in lentic water bodies with medium organic matter content and neutral pH. The species seems to prefer mesotrophic waters with low to medium electrolyte content and oligosaprobous. The species morphology and identity is documented in a series of light microscopic (LM) images and for the first time under a scanning electron microscope (SEM).

Sajmiste as a European site of Holocaust remembrance

The article analyzes the peculiarities of the destruction of Serbian Jews during Second Wolrd War in the local and European context. Of all the sites in Serbia relevant to the destruction of the Serbian Jews, Sajmiste is the most important. After the consideration of the attitude of Germans and Nedic?s regime toward Jews and ?Gypsies? in the context of the Final Solution, the author highlights that the Sajmiste internment camp was transformed into a local death camp-the only such site outside the territories of Poland and the Soviet Union. Serbia was the one country outside Poland and the Soviet Union where all Jewish victims were killed on the spot without deportation. It was the first country after Estonia to be declared ?judenfrei.? Moreover, in Serbia the German army was not only complicit in the Holocaust but was in fact the main instigator and executioner in the killing of the Jewish men. For this reason, in particular, Sajmiste is a unique site for Holocaust remembrance not only in the Serbian but also in the European context.