Speaker
Description
"Coronal dimmings, also called transient coronal holes, are well documented following eruptions (e.g. Veronig et al. 2025). Between 17 and 18 March 2022, a coordinated Solar Orbiter–Hinode–IRIS campaign monitored the formation of a coronal dimming following a filament eruption (Ngampoopun et al. 2023).
We investigate whether the eruption produced a coronal-hole-like behaviour in the initially quiet Sun by analysing the chromospheric and coronal response prior and during the dimming.
In SDO/AIA 193 Å images we found, close to the dimming-quiet Sun boundary, a factor of 1.6 ± 0.2 times more EUV brightenings compared to the number of brightenings in the same area prior to the eruption. Such an increase was not observed in SDO/AIA 171 Å and Solo/HRI 174 Å, giving a temperature constraint. Existing bright points appeared relatively unaffected by the change in the magnetic environment. The coronal spectroscopic data of the dimming have converged towards typical coronal hole values: the Doppler velocities changed from 0 to -3 km/s (upflow) and the intensity ratio Si X/S X decreased from 2.1 to 1.4. The chromospheric Mg II emission remained indistinguishable from quiet Sun.
We suggest that the interaction with the open fields of the dimming occurred mainly at higher altitudes than the bright points, and that interchange reconnection at the dimming boundary produced brightenings at 193 Å."