Speaker
David Graham
(INAF Osservatorio Astrofisico di Arcetri)
Description
We follow up on our recent analysis of the X-Class flare SOL2014-09-10T17:45, where
we studied the impulsive phase dynamics of tens of individual flaring kernels", in
both coronal (Fe XXI) and chromospheric (MgII) lines observed at high cadence with
IRIS. We concentrate here on the chromospheric aspect of the phenomenon, extending
the analysis to multiple spectral lines of Mg II, Fe II, Si I, C II. We show that
many flaring kernels display high velocity downflows in the spectra of all these
chromospheric lines, exhibiting distinct, transient and strongly redshifted spectral
components. From preliminary modelling using RADYN with the thick-target
interpretation, the presence of two spectral components appears to be consistent with
a high flux beam of accelerated electrons. In particular the highest energy electrons
can heat the denser, lower layers of the atmosphere, while the bulk of the beam
energy, deposited higher in the atmosphere, is sufficient to produce chromospheric
evaporation with a corresponding condensation."
Primary author
David Graham
(INAF Osservatorio Astrofisico di Arcetri)
