http://arxiv.org/abs/1709.03864
$\delta$-sunspots are known to be favourable locations for fast and energetic events like flares and CMEs. The photosphere of this type of sunspots has been thoroughly investigated in the past three decades. The atmospheric conditions in the chromosphere are not so well known, however. his study is focused on the chromosphere of a $\delta$-sunspot that harbours a series of fan-shaped jets in its penumbra . The aim of this study is to establish the magnetic field topology and the temperature distribution in the presence of jets in the photosphere and the chromosphere. We use data from the Swedish 1-m Solar Telescope (SST) and the Solar Dynamics Observatory. We invert the spectropolarimetric FeI 6302~\AA\ and CaII ~8542~\AA\ data from the SST using the the non-LTE inversion code NICOLE to estimate the magnetic field configuration, temperature and velocity structure in the chromosphere. A loop-like magnetic structure is observed to emerge in the penumbra of the sunspot. The jets are launched from the loop-like structure. Magnetic reconnection between this emerging field and the pre-existing vertical field is suggested by hot plasma patches on the interface between the two fields. The height at which the reconnection takes place is located between $\log \tau_{500} = -2$ and $\log \tau_{500} = -3$. The magnetic field vector and the atmospheric temperature maps show a stationary configuration during the whole observation.
C. Robustini, J. Leenaarts and J. Rodriguez
Wed, 13 Sep 17
10/72
Comments: 12 pages, 15 figures. Recommended for publication in A&A