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Temperature and Density Diagnostics with SECCHI EUVI
J.S. Newmark
Naval Research Laboratory
(202) 767-0244
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EUVI Temperature Response
Contaminating Lines (Mg VII, Si VII)
Contaminating Line (Si XI)
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EIT Temperature Response
Contaminating Lines (Mg VII, Si VII)
Contaminating Line (Si XI)
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Differential Emission Measure
• I(ergs cm-2 s-1 sr-1) = F(atomic physics)* DEM, DEM = Ne2dl/dlogT, assumes optically thin, steady state equilibrium, atomic physics = CHIANTI
• Applications: Solar absolute intensity maps- lines or bandpasses, thermal structure of the solar atmospheric energy balance, model radio thermal bremsstrahlung emission – appropriate for “stable” structures or long term studies, not FLARE related events.
• Loop temperatures and coronal heating
• EIT derived DEMs - Cook et al. 1999, 2003, forward modeling, full disk, pixel-by-pixel DEM maps from 80,000 K - 2.5 MK
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Intensity Error Maps
(Obs-Model)/Obs
Largest errors due to low S/N
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Comparison DEM and EM
Isothermal Emission Measure Determined from single ratio – note multi-thermal nature
Ratio emission measureEM/0.3 (LogT range)
Ratio emission measureEM*0.7/0.3 (<EM> over LogT distribution)
Isothermal EM = DEM x LogT
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DEM and Irradiance Software
• Solarsoft + CHIANTI
• EUVI DEM Software
– EUVI_DEM_TOOL
– EUVI_LINE_MAP
– EUVI_IRRAD_SPEC
– 1024x1024x25 array takes ~2 minutes
– User’s beware – please read assumptions in code, e.g. abundance, ionization equilibrium, helium enhancement, etc.
• 170 – 340 Å spectra, 10 Å bins
– Website