Objective: To obtain plasma diagnostics in microflares and small flares.
Description:
The evolution of small flares observed with Hinode/EIS and SDO/AIA and EVE has been studied extensively by Mason, Del Zanna and colleagues (cf Del Zanna, 2008, Del Zanna et al, 2011, Petkaki et al, 2012).
Hinode/EIS is able to provide information on plasma parameters (Ne, DEM) and flows, ie chromospheric evaporation (blue-shifted emission) which can be matched against theoretical models of solar flares. The temporal evolution can be tracked with SDO, together with further information on the structure and evolution (e.g. temperature).
IRIS provides a powerful tool to study the emission at cooler temperatures, in particular the from temperatures characteristic of the Transition Region (TR, 10^5K). Spectral lines from SiIV and OIV are prominent in the FUV band. The transition region responds directly during the impulsive phase of the flare (probably as electron beams hit and heat the chromosphere). The electron density in the TR emission can be measured from the OIV lines, and the line profiles provide information on flows.
In addition the FeXXI spectral line at 1354.1A is ideal for studying chromospheric emission during solar flares (Mason et al, 1986, as seen with SMM/UVSP). In IRIS, the spectral line profiles can be easily resolved in the FUV, and also there are cooler lines (chromospheric and photospheric) which can be used as a reference wavelength for velocity shifts in TR and flare lines.
Plasma parameters from Hinode/EIS and IRIS could be matched against each other (for example electron densities from TR and hotter, coronal emission). Small flares and micro-flares could be caused by flux emergence. The measurement of the magnetic field (from Hinode/SOT or SDO/HMI) would provide very useful information in this regard.
In this collaborative study, we aim to study small flares and microflares, which occur frequently in active regions (particularly new ones). We aim to maximize the information which we can derive from imaging and spectroscopic observations by combining observations from Hinode, IRIS and SDO (if possible also with RHESSI).
Del Zanna, 2008, A&A, 481, L69
Del Zanna et al, 2011, A&A, 526, 1
Petkaki et al, 2012, A&A, 547, 25
Mason et al, 1986, ApJ, 309, 435 |
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