摘要：Context. Magnetic reconnection during flares takes place in the corona, but a substantial part of flare energy is deposited in the chromosphere. However, high-resolution spectro-polarimetric chromospheric observations of flares are very rare. The most used observables are Ca II8542 Å and He I10830 Å.Aims. We aim to study the chromosphere during a C3.6 class flare via spectro-polarimetric observations of the He ID3line.Methods. We present the first SST/CRISP spectro-polarimetric observations of He ID3. We analyzed the data using the inversion code HAZEL, and estimate the line-of-sight velocity and the magnetic field vector.Results. Strong He ID3emission at the flare footpoints, as well as strong He ID3absorption profiles tracing the flaring loops are observed during the flare. The He ID3traveling emission kernels at the flare footpoints exhibit strong chromospheric condensations of up to ∼60 km s−1at their leading edge. Our observations suggest that such condensations result in shocking the deep chromosphere, causing broad and modestly blueshifted He ID3profiles indicating subsequent upflows. A strong and rather vertical magnetic field of up to ∼2500 G is measured in the flare footpoints, confirming that the He ID3line is likely formed in the deep chromosphere at those locations. We provide chromospheric line-of-sight velocity and magnetic field maps obtained via He ID3inversions. We propose a fan-spine configuration as the flare magnetic field topology.Conclusions. The He ID3line is an excellent diagnostic to study the chromosphere during flares. The impact of strong condensations on the deep chromosphere has been observed. Detailed maps of the flare dynamics and the magnetic field are obtained.
关键词：enSun: flaresSun: atmosphereSun: activitySun: magnetic fieldsradiative transferline: formation
