Freiburg 2008 – scientific programme
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EP: Fachverband Extraterrestrische Physik
EP 7: The Sun and Heliosphere I
EP 7.3: Talk
Tuesday, March 4, 2008, 15:00–15:15, KGI-Aula
Single-lobe Stokes-V profiles in the solar atmosphere — •Reza Rezaei, Wolfgang Schmidt, and Rolf Schlichenmaier — Kiepenheuer-Institut für Sonnenphysik, Freiburg, Germany
Stokes polarimetry provides information about the magnetic field and its interaction with the plasma in the solar photosphere and chromosphere. While most of the observed Stokes-V profiles in active regions and the network are nearly antisymmetric, strongly asymmetric and abnormal V profiles are common in the inter-network. We observed a small quiet Sun region close the center of the solar disk with the German Vacuum Tower Telescope in Tenerife on July 07, 2006. Stokes profiles of the neutral iron lines at 630.15 and 630.25 nm and the intensity profile of the Ca II H line at 396.8 nm were recorded strictly simultaneously with the two channels of POlarimetric Littrow Spectrograph. We find that half of all profiles with an amplitude above the 3σ noise level are one-lobe profiles. Among them, about 78 % have a blue lobe only and 22 % have only a red lobe. There are several examples, where the amplitude of the blue-lobe-only profile exceeds 1 % of the continuum while there is no such case for the red-lobe-only profiles. The mean amplitude of the blue-lobe-only profiles (0.30 %Ic) is also larger than the mean amplitude of the red-lobe-only profiles (0.26 %Ic). In addition to the above mentioned case, we find new categories of abnormal Stokes-V profiles in which there are significant differences between the Fe I 630.15 and 630.25 nm lines. There are indications that the degree of asymmetry and the fraction of abnormal V profiles increase with decreasing magnetic flux and increasing spatial resolution.