Institution(s): 1. KIS, Freiburg
Magnetic activity is a fundamental feature of stars with outer convection envelopes and fully convective red and brown dwarfs. It is detected directly through the Zeeman effect and indirectly through brightness variability due to spots and flares. Recently we have demonstrated a technique capable of recovering 3D topology of active regions on cool stars (temperature and magnetic field) using inversions of atomic and molecular lines forming at different heights in the atmosphere (Berdyugina 2011). Here we extend this technique to the chromosphere by including an inversion of chromospheric emission during active states (e.g., flares). We apply this technique to several very active red and brown dwarfs and recover 3D magnetic structures in the photosphere and chromosphere. We compare the recovered loop structure and properties with those observed in solar active regions.