Letter to the Editor

Opposite magnetic polarity of two photospheric lines in single spectrum of the quiet Sun

Kiepenheuer-Institut für Sonnenphysik, Schöneckstr. 6, 79104 Freiburg, Germany e-mail: [rrezaei;schliche;wolfgang;steiner]@kis.uni-freiburg.de

Received: 8 March 2007
Accepted: 24 April 2007

Abstract

Aims.We study the structure of the photospheric magnetic field of the quiet Sun by investigating weak spectro-polarimetric signals.

Methods.We took a sequence of Stokes spectra of the 630.15 nm and 630.25 nm lines in a region of quiet Sun near the disk center, using the POLIS spectro-polarimeter at the German VTT on Tenerife. The line cores of these two lines form at different heights in the atmosphere. The 3σ noise level of the data is about 1.8  10^-3 I_c.

Results.We present co-temporal and co-spatial Stokes-V profiles of the  630 nm line pair, where the two lines show opposite polarities in a single spectrum. We compute synthetic line profiles and reproduce these spectra with a two-component model atmosphere: a non-magnetic component and a magnetic component. The magnetic component consists of two magnetic layers with opposite polarity: the upper one moves upwards while the lower one moves downward. In-between, there is a region of enhanced temperature.

Conclusions.The Stokes-V line pair of opposite polarity in a single spectrum can be understood as a magnetic reconnection event in the solar photosphere. We demonstrate that such a scenario is realistic, but the solution may not be unique.