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SUMMARY:Solar Flare Ion Temperatures - Alex Russell (St. Andrews)
DTSTART:20251103T160000Z
DTEND:20251103T170000Z
UID:TALK237604@talks.cam.ac.uk
CONTACT:Roger Dufresne
DESCRIPTION: This talk presents work recently published in ApJL where we h
 ave argued that the ion temperature is several times the local electron te
 mperature in the hot onset phase and in the above-the-loop region of solar
  flares. The talk considers: \n  (1) the evidence of spectral line Doppler
  widths (“nonthermal” broadening)\;\n  (2) evidence for “universal
 ” ion and electron temperature increase scaling relations for magnetic r
 econnection in the solar wind\, Earth’s magnetopause\, Earth’s magneto
 tail\, and numerical simulations\; and \n  (3) thermal equilibration times
  for onset and above-the-loop densities\, which are much longer than previ
 ous estimates based on soft X-ray flare loops.\n\nWe conclude that the ion
  temperature is likely to reach 60 MK or greater and that it may represent
  a substantial part of spectral line widths\, significantly contributing t
 o solving the long-standing issue of the excess nonthermal broadening in f
 lare lines. The talk will also include an overview of new preliminary work
  addressing multi-temperature flare modelling.\n\nRelated paper: https://d
 oi.org/10.3847/2041-8213/adf74a Russell et al. 2025\, ApJ Letters\, 990:L3
 9. Co-authors: Vanessa Polito\, Paola Testa\, Bart De Pontieu and Sergey B
 elov
LOCATION:MR14 DAMTP and online
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