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 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" Obs.date 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 2014ApJ...797...50A Cat. J/ApJ/797/50
Aschwanden et al. Paper II. 2015ApJ...802...53A 2015ApJ...802...53A Cat. J/ApJ/802/53
Aschwanden et al. Paper III. 2016ApJ...832...27A 2016ApJ...832...27A This catalog
Aschwanden M.J. Paper IV. 2016ApJ...831..105A 2016ApJ...831..105A Cat. J/ApJ/831/105
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 01-Feb-2017