Statistically-derived flaring chromospheric-coronal density structure from non-thermal X-ray observations of the Sun

Abstract

For the first time, we have used RHESSI's spatial and energy resolution to determine the combined chromospheric and coronal density profile of the flaring solar atmosphere in a statistical manner, using a dataset of 838 flares observable in hard X-rays above 25 keV. Assuming the thick-target beam model, our "average flaring atmosphere" was found to have density scale heights of 131+/-16 km at low altitudes (chromosphere, up to ~1-1.5 Mm above photosphere), and of 5-6 Mm at high altitudes (corona, above ~2-3 Mm). Assuming a unit step change in ionization level, modeling yields a height of 1.3+/-0.2 Mm for the transition between fully neutral to fully-ionized atmosphere. Furthermore, centroids of emission above 50 keV, produced by electrons of similar or higher energies, are located mostly in a small region ~0.5 Mm in vertical extent, where neutral densities are beyond 3x10^13 cm^-3.

8 pages, 4 figures. Published in Astrophysical Journal

References in corpus (4)

• Relations between concurrent hard X-ray sources in solar flares
• RHESSI Observation of Chromospheric Evaporation
• Chromospheric magnetic field and density structure measurements using hard X-rays in a flaring coronal loop
• The x-ray detectability of electron beams escaping from the sun

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