Coronal Abundance Fractionation Linked to Chromospheric Transverse MHD Waves in a Solar Active Region Observed with FISS/GST and EIS/Hinode

TL;DR

This study demonstrates a strong correlation between coronal abundance fractionation and chromospheric transverse MHD waves, supporting the theory that the FIP effect is driven by ponderomotive forces from these waves in solar active regions.

Contribution

It provides observational evidence linking chromospheric transverse MHD waves to coronal abundance fractionation, validating the ponderomotive force model for the FIP effect.

Findings

High FIP fractionation regions coincide with areas of transverse MHD waves.

Approximately 43% of observed waves are low-frequency and downward-propagating.

Waves are mainly observed near loop footpoints in sunspot regions.

Abstract

Elemental abundances in the solar corona differ from those in the photosphere, with low first ionization potential (FIP) elements being enhanced, a phenomenon known as the FIP effect. This enhancement is attributed to ponderomotive forces linked to magnetohydrodynamic (MHD) waves, particularly incompressible transverse waves. Our study investigates the relationship between coronal abundance fractionation and chromospheric transverse MHD waves by examining the spatial correlation between FIP fractionation and these waves and by analyzing their properties to test the ponderomotive force model. We used H alpha data from the Fast Imaging Solar Spectrograph at the Goode Solar Telescope to detect chromospheric transverse MHD waves and \ion{Si}{X} (low FIP) and \ion{S}{X} (high FIP) spectra from Hinode EUV Imaging Spectrometer to determine relative abundances in an active region. Extrapolated linear force free magnetic fields from Solar Dynamics Observatory/Helioseismic and Magnetic Imager magnetograms further linked the observed chromospheric waves with coronal composition. Approximately 400 wave packets were identified and characterized by their period, velocity amplitude, propagation speed, and direction. These incompressible or weakly compressible waves were mainly observed near loop footpoints in the sunspot penumbra and superpenumbral fibrils. Regions of high FIP fractionation coincided with closed magnetic fields where these waves were present, and low-frequency, downward-propagating waves comprised about 43/% of the total. Our results demonstrate a strong correlation between coronal abundance fractionation and chromospheric transverse MHD waves, supporting the view that the FIP effect is driven by the ponderomotive force from these waves.