E. Antonucci et al., INTERPRETATION OF THE OBSERVED PLASMA TURBULENT VELOCITIES AS A RESULT OF MAGNETIC RECONNECTION IN SOLAR-FLARES, The Astrophysical journal, 456(2), 1996, pp. 833-839
One of the distinctive features of magnetic reconnection in current sh
eets, which has been proposed as the primary energy source in solar fl
ares, is the presence of fast plasma outflows, or jets, whose velociti
es are nearly equal to the Alfven speed and depend mainly on the elect
ron and ion temperatures inside the current sheet. We briefly discuss
the outflows that originate during the reconnection process in the hig
h-temperature turbulent current sheet (HTTCS) approximation, both for
preflare and ''hot'' phase conditions. Outflows can give rise to plasm
a velocity distributions with equal and opposite components along the
line of sight, and therefore they can, in this way, create a symmetric
, nonthermal broadening in the soft X-ray lines observed during solar
flares. A comparison of the nonthermal profiles of the Fe xxv emission
lines observed at flare onset with the predictions of the HTTCS model
suggests that the observed nonthermal broadenings are consistent with
the presence in the flare region of several small-scale or one (or a
few) curved, large-scale reconnecting current sheets with internal tem
perature less than or equal to 8 x 10(7) K. The velocities of the outf
lows at the emergence of the reconnecting current sheets are inferred
to be less than or equal to 1100 km s(-1).