The magnetic topology of the inverse Evershed flow

Context. The inverse Evershed flow (IEF) is a mass motion towards sunspots at chromospheric heights. Aims. We combined high-resolution observations of NOAA 12418 from the Dunn Solar Telescope and vector magnetic field measurements Helioseismic Magnetic Imager (HMI) to determine driver IEF. Methods. derived line-of-sight (LOS) velocities spectra H α Ca II IR. HMI data were used in non-force-free extrapolation track closed lines near sunspot active region. determined their length height, located inner outer foot points, along them. Results. related IEF reach on average height 3 megameter (Mm) over 13 Mm. (outer) points are 1.2 (1.9) radii. strength difference Δ B between +400 G. temperature T anti-correlated with an value −100 K. pressure p dominated by primarily positive driving force 1.7 kPa average. predicted reproduce LOS 2–10 km s −1 square-root dependence. Conclusions. find that driven connecting network elements penumbra gas results as classical siphon scenario.