J/ApJ/802/53 Global energetics of solar flares. II. (Aschwanden+, 2015)
Global energetics of solar flares:
II. Thermal energies.
Aschwanden M.J., Boerner P., Ryan D., Caspi A., McTiernan J.M., Warren H.P.
<Astrophys. J., 802, 53 (2015)>
=2015ApJ...802...53A 2015ApJ...802...53A
ADC_Keywords: Sun ; Stars, flare ; Ultraviolet
Keywords: plasmas; radiation mechanisms: thermal; Sun: flares; Sun: UV radiation
Abstract:
We present the second part of a project on the global energetics of
solar flares and coronal mass ejections that includes about 400 M- and
X-class flares observed with the Atmospheric Imaging Assembly (AIA)
onboard the Solar Dynamics Observatory (SDO) during the first 3.5yr of
its mission. In this Paper II we compute the differential emission
measure (DEM) distribution functions and associated multithermal
energies, using a spatially-synthesized Gaussian DEM forward-fitting
method. The multithermal DEM function yields a significantly higher
(by an average factor of ∼14), but more comprehensive (multi-) thermal
energy than an isothermal energy estimate from the same AIA data. We
find a statistical energy ratio of Eth/Ediss∼2-40% between the
multithermal energy Eth and the magnetically dissipated energy
Ediss, which is an order of magnitude higher than the estimates of
Emslie et al. (2012ApJ...759...71E 2012ApJ...759...71E). For the analyzed set of M- and
X-class flares we find the following physical parameter ranges:
L=108.2-109.7cm for the length scale of the flare areas,
Tp=105.7-107.4K for the DEM peak temperature,
Tw=106.8-107.6K for the emission measure-weighted temperature,
np=1010.3-1011.8/cm3 for the average electron density,
EMp=1047.3-1050.3/cm3 for the DEM peak emission measure, and
Eth=1026.8-1032.0erg for the multithermal energies. The deduced
multithermal energies are consistent with the RTV scaling law
Eth,RTV=73x10-10Tp3Lp2, which predicts extremal values of
Eth,max∼1.5x1033erg for the largest flare and
Eth,min∼1x1024erg for the smallest coronal nanoflare. The size
distributions of the spatial parameters exhibit powerlaw tails that
are consistent with the predictions of the fractal-diffusive
self-organized criticality model combined with the RTV scaling law.
Description:
The dataset we are analyzing for this project on the global energetics
of flares includes all M- and X-class flares observed with the Solar
Dynamics Observatory (SDO) during the first 3.5yr of the mission (2010
June 1 to 2014 January 31), which amounts to 399 flare events, as
described in Paper I (Aschwanden et al. 2014, J/ApJ/797/50). We
attempt to calculate the thermal energies in all 399 cataloged events,
but we encountered eight events with incomplete or corrupted
Atmospheric Imaging Assembly (AIA) data, so that we are left with 391
events suitable for thermal data analysis.
AIA provides EUV images corresponding to an effective spatial
resolution of ∼1.6".
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 63 391 Thermal energy parameters of 391 M and X-class
flare events
--------------------------------------------------------------------------------
See also:
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)
J/A+A/304/563 : Cool X-ray flares of Sun with GOES (Phillips+, 1995)
http://aia.lmsal.com/ : Atmospheric Imaging Assembly home page
http://www.lmsal.com/~aschwand/RHESSI/flare_energetics.html : Global Flare
Energetics Survey home page project
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq [1/399] Running sequence number
5- 14 A10 "YYYY/MM/DD" Flare.date Flare start date
16- 20 A5 "h:m" Flare.time Flare start time
22- 25 A4 --- Cl Geostationary Operational Environmental
Satellite (GOES) SXR class (M1-X6.9)
27- 32 A6 --- Pos Heliographic position
34- 37 F4.1 Mm L [1.7/46] Length scale of the flare area
39- 42 F4.1 MK Tp [0.5/28.2] Peak temperature
44- 47 F4.1 MK Tw [5.7/41.6] Electron Measure-weighted
temperature
49- 52 F4.1 [cm-3] log(ne) [10.3/11.8] Log of the Electron density
54- 57 F4.1 [cm-3] log(EM) [47.3/50.3] Log of the Emission measure
59- 63 F5.1 [10+23J] log(Eth) [0.2/215.3] Log of the Thermal energy;
in 1e+30erg unit
--------------------------------------------------------------------------------
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 This catalog
Aschwanden et al. Paper III. 2016ApJ...832...27A 2016ApJ...832...27A Cat. J/ApJ/832/27
Aschwanden M.J. Paper IV. 2016ApJ...831..105A 2016ApJ...831..105A Cat. J/ApJ/831/105
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 22-Jul-2015