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J/ApJ/832/27     Global energetics of solar flares. III.     (Aschwanden+, 2016)

Global energetics of solar flares. III. Nonthermal energies. Aschwanden M.J., Holman G., O'Flannagain A., Caspi A., McTiernan J.M., Kontar E.P. <Astrophys. J., 832, 27-27 (2016)> =2016ApJ...832...27A (SIMBAD/NED BibCode)
ADC_Keywords: Sun ; Stars, flare ; Models Keywords: radiation mechanisms: nonthermal; Sun: flares; Sun: particle emission; Sun: X-rays, gamma rays 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. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 88 190 Nonthermal energy parameters derived in 191 flare events observed with RHESSI
See also: J/ApJ/831/105 : Global energetics of solar flares. IV. CME (Aschwanden, 2016) J/ApJ/802/53 : Global energetics of solar flares. II. (Aschwanden+, 2015) J/A+A/574/A37 : Movies of 2012-10-16 solar flare (Dalmasse+, 2015) J/ApJ/797/50 : Global energetics of solar flares. I. (Aschwanden+, 2014) J/ApJ/774/L27 : Solar flares predictors (Yang+, 2013) J/ApJ/759/69 : Solar electron events (1995-2005) with WIND/3DP (Wang+, 2012) J/ApJ/757/94 : Solar flares observed with GOES and AIA (Aschwanden, 2012) J/ApJ/747/L41 : Solar flares probabilities (Bloomfield+, 2012) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 3 I3 --- Seq Index number 5- 14 A10 "Y/M/D" Date of Flare start 16- 20 A5 "h:m" Obs.time Time of Flare start 22- 25 A4 --- Cl GOES class 27- 32 A6 --- Pos Heliographic position 34- 38 I5 s Dur [160/20740] Soft X-ray flare duration 40- 44 I5 ct/s PkCts [30/53158] Peak counts 46- 52 E7.1 ct/s Cts Total counts 54- 55 I2 keV LowE [6/16] Lower bounds of fitted energy range 57- 58 I2 keV UpE [20/50] Upper bounds of fitted energy range 60- 63 F4.1 keV Cutoff [1.6/11.7] Warm-target lower cutoff energy (1) 65- 71 E7.1 10-7J Ewt Nonthermal energy, Ewt; in ergs 73- 79 F7.4 --- ERatio1 [0.002/76]?=0 Ratio of thermal to warm-target nonthermal energies, Eth/Ewt 81 A1 --- f_ERatio1 [*] Flag on ERatio1 (2) 83- 88 F6.3 --- ERatio2 [0.002/39]?=0 Ratio of warm-target nonthermal to magnetic energies, Ewt/Emag
Note (1): For a mean temperature of Te = 8.6 MK in flaring active regions. Note (2): * = Questionable solar flare event, detected in the front detectors without position.
History: From electronic version of the journal References: Aschwanden et al. Paper I. 2014ApJ...797...50A Cat. J/ApJ/797/50 Aschwanden et al. Paper II. 2015ApJ...802...53A Cat. J/ApJ/802/53 Aschwanden et al. Paper III. 2016ApJ...832...27A This catalog Aschwanden M.J. Paper IV. 2016ApJ...831..105A Cat. J/ApJ/831/105
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 01-Feb-2017
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