Speaker: Dr. Malcolm Druett (Sheffield University)

Title: Flare evaporation, condensations, and ribbons

Abstract: Evaporation and condensation processes are highly dynamic in solar flares, and both can be investigated through the chromospheric spectral lines and flare ribbons.
Evaporation occurs from a source of chromospheric flare ribbon material. The key mechanism(s) driving the evaporation are not neatly resolved, with plausible candidates including non-thermal beams of particles, field-aligned thermal conduction, Alfven waves, and reconnection outflow jets. We use state-of-the-art multi-dimensional MHD simulations to investigate differences in flare evolution that result from different energy transport mechanisms.
Condensations are seen in post flare loop arcades, with coronal rain events in which condensed material flows down towards the bright ribbons. We present the variations of flare ribbon spectral profiles using high-resolution spectro-polarimetric SST observations and sub-second cadence IRIS satellite spectra. These are used to track condensation flows and ribbon features. We also present so-called “chromospheric condensations” in the lower atmosphere, interpreting them through our multi-dimensional MHD models. We provide an updated schematic to interpret the formation of flare ribbons from the spectra.
Ongoing developments of our simulations are introduced
(1) improving the lower atmosphere used, and the initial reconnection location
(2) including asymmetry and more realistic chromospheric magnetic field parameters,
(3) beam particle energy budgets and spectra informed by reconnection and particle acceleration modelling.
(4) building a framework to estimate the ionisation degree, and radiative energy losses and gains in the chromosphere from detailed 1D RADYN models.

Note: Host: Alex Pietrow

• Date:
  Sept. 4, 2025, 2:30 p.m. – 4 p.m.
  
  
• Location:

  AIP; Kirch building, Conference room

  
  
• Contact:
  Julián Alvarado-Gómez
  julian.alvarado-gomez@aip.de