VizieR Online Data Catalog: Global energetics of solar flares. III. (Aschwanden+, 2016)
Abstract
This study entails the third part of a global flare energetics project, in which Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) data of 191 M and X-class flare events from the first 3.5yrs of the Solar Dynamics Observatory mission are analyzed. We fit a thermal and a nonthermal component to RHESSI spectra, yielding the temperature of the differential emission measure (DEM) tail, the nonthermal power-law slope and flux, and the thermal/nonthermal cross-over energy eco. From these parameters, we calculate the total nonthermal energy Ent in electrons with two different methods: (1) using the observed cross-over energy eco as low-energy cutoff, and (2) using the low-energy cutoff ewt predicted by the warm thick-target bremsstrahlung model of Kontar et al. Based on a mean temperature of Te=8.6MK in active regions, we find low-energy cutoff energies of ewt=6.2+/-1.6keV for the warm-target model, which is significantly lower than the cross-over energies eco=21+/-6keV. Comparing with the statistics of magnetically dissipated energies Emag and thermal energies Eth from the two previous studies, we find the following mean (logarithmic) energy ratios with the warm-target model: Ent=0.41Emag, Eth=0.08Emag, and Eth=0.15Ent. The total dissipated magnetic energy exceeds the thermal energy in 95% and the nonthermal energy in 71% of the flare events, which confirms that magnetic reconnection processes are sufficient to explain flare energies. The nonthermal energy exceeds the thermal energy in 85% of the events, which largely confirms the warm thick-target model.
(1 data file).- Publication:
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VizieR Online Data Catalog
- Pub Date:
- February 2017
- DOI:
- 10.26093/cds/vizier.18320027
- Bibcode:
- 2017yCat..18320027A
- Keywords:
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- Sun;
- Stars: flare;
- Models