Inverse FIP effect plasma in the solar atmosphere: a synthesis of current understanding and new insights from AR 11967

Wave–plasma interactions and energy transport are fundamental processes in stellar atmospheres, shaping elemental composition through the first ionization potential (FIP) and inverse FIP (IFIP) effects. Although stellar measurements provide global evidence of abundance anomalies, the Sun offers a unique local laboratory in which to resolve how these processes operate on small spatial and temporal scales. In this overview, we summarize the current state of knowledge of the IFIP effect, its observational signatures and the theoretical framework that underpins it. We then present new insights from a detailed case study of active region (AR) NOAA AR 11967, where combined Hinode/extreme-ultraviolet imaging spectrometer (EIS), IRIS, SDO/AIA and Fermi/GBM observations and IRIS2+ inversions indicate that torsional Alfvén waves generated below the chromospheric fractionation region can account for the highly localized IFIP effect plasma observed on the Sun. This analysis highlights the possible role of sub-chromospheric processes in the formation of the IFIP effect on the Sun and informs pathways for understanding similar mechanisms in the coronae of active M dwarfs. This article is part of the Theo Murphy meeting issue ‘Solar atmospheric abundances in space and time’.