Speaker
Harry Warren
(NRL)
Description
We exploit the high spatial resolution and high cadence of IRIS to investigate the
response of the transition region and chromosphere to energy deposition during
several small flares. We find that during the impulsive phase of these events the
intensities of the C II 1334 and Si IV 1403 emission lines are characterized by
numerous, small-scale impulsive bursts typically lasting 60 s or less, followed by a
slower decay over several minutes. These variations in intensity are usually
accompanied by redshifts of 20–40 km/s, although some blueshifted profiles are also
observed. For one particularly well observed event we combine the IRIS observations
with co-temporal measurements of hard X-ray emission from RHESSSI, transition region
density from EIS, and high-temperature coronal loops with XRT and AIA to constrain 1D
hydrodynamic models of loop evolution. Many aspects of the observations can be
explained with simple heating scenarios, but some cannot. The simulated Doppler
shifts, for example, show very short-duration redshifts during the initial phase of
the heating while the observed redshifts persist over several minutes.
Primary author
Harry Warren
(NRL)
