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Multi-Wavelength Observations of the Spatio-Temporal Evolution of Solar Flares with AIA/SDO:I. Universal Scaling Laws of Space and Time Parameters  

Markus J. Aschwanden   Submitted: 2013-08-22 11:43

We extend a previous statistical solar flare study of 155 GOES M- and X-class flares observed with AIA/SDO (Aschwanden 2012) to all 7 coronal wavelengths (94, 131, 171, 193, 211, 304, 335 ang ) to test the wavelength-dependence of scaling laws and statistical distributions. Except for the 171 and 193 ang wavelengths, which are affected by EUV dimming caused by coronal mass ejections (CMEs), we find near-identical size distributions of geometric (lengths L, flare areas A, volumes V, fractal dimension D2), temporal (flare durations T), and spatio-temporal parameters (diffusion coefficient kappa, spreading exponent eta, and maximum expansion velocities vmax) in different wavelengths, which are consistent with the universal predictions of the fractal-diffusive avalanche model of a slowly-driven self-organized criticality (FD-SOC) system, i.e., N(L) propto L-3, N(A) propto A-2, N(V) propto V-5/3, N(T) propto T-2, D_2=3/2, for a Euclidean dimension d=3. Empirically we find also a new strong correlation kappa propto L0.94pm0.01 and the 3-parameter scaling law L propto kappa T0.1, which is more consistent with the logistic-growth model than with classical diffusion. The findings suggest long-range correlation lengths in the FD-SOC system that operate in the vicinity of a critical state, which could be used for predictions of individual extreme events. We find also that eruptive flares (with accompanying CMEs), have larger volumes V, longer flare durations T, higher EUV and soft X-ray fluxes, and somewhat larger diffusion coefficients kappa than confined flares (without CMEs).

Authors: Aschwanden,J.M., Zhang, J., Liu,K.
Projects: None

Publication Status: (2013), ApJ 775, 23
Last Modified: 2013-10-07 18:23
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Multi-Wavelength Observations of the Spatio-Temporal Evolution of Solar Flares with AIA/SDO:I. Universal Scaling Laws of Space and Time Parameters  

Markus J. Aschwanden   Submitted: 2013-08-22 11:43

We extend a previous statistical solar flare study of 155 GOES M- and X-class flares observed with AIA/SDO (Aschwanden 2012) to all 7 coronal wavelengths (94, 131, 171, 193, 211, 304, 335 ang ) to test the wavelength-dependence of scaling laws and statistical distributions. Except for the 171 and 193 ang wavelengths, which are affected by EUV dimming caused by coronal mass ejections (CMEs), we find near-identical size distributions of geometric (lengths L, flare areas A, volumes V, fractal dimension D2), temporal (flare durations T), and spatio-temporal parameters (diffusion coefficient kappa, spreading exponent eta, and maximum expansion velocities vmax) in different wavelengths, which are consistent with the universal predictions of the fractal-diffusive avalanche model of a slowly-driven self-organized criticality (FD-SOC) system, i.e., N(L) propto L-3, N(A) propto A-2, N(V) propto V-5/3, N(T) propto T-2, D_2=3/2, for a Euclidean dimension d=3. Empirically we find also a new strong correlation kappa propto L0.94pm0.01 and the 3-parameter scaling law L propto kappa T0.1, which is more consistent with the logistic-growth model than with classical diffusion. The findings suggest long-range correlation lengths in the FD-SOC system that operate in the vicinity of a critical state, which could be used for predictions of individual extreme events. We find also that eruptive flares (with accompanying CMEs), have larger volumes V, longer flare durations T, higher EUV and soft X-ray fluxes, and somewhat larger diffusion coefficients kappa than confined flares (without CMEs).

Authors: Aschwanden,J.M., Zhang, J., Liu,K.
Projects: None

Publication Status: (2013), ApJ 775, 23
Last Modified: 2014-03-25 16:26
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Optimization of Curvi-Linear Tracing Applied to Solar Physics and Biophysics  

Markus J. Aschwanden   Submitted: 2013-07-18 12:23

We developed an automated pattern recognition code that is particularly well suited to extract one-dimensional curvi-linear features from two-dimensional digital images. A former version of this {sl Oriented Coronal CUrved Loop Tracing (OCCULT)} code was applied to spacecraft images of magnetic loops in the solar corona, recorded with the NASA spacecraft {sl Transition Region And Coronal Explorer (TRACE)} in extreme ultra-violet wavelengths. Here we apply an advanced version of this code ({sl OCCULT-2}) also to similar images from the {sl Solar Dynamics Observatory (SDO)}, to chromospheric H- α images obtained with the {sl Swedish Solar Telescope (SST)}, and to microscopy images of microtubule filaments in live cells in biophysics. We provide a full analytical description of the code, optimize the control parameters, and compare the automated tracing with visual/manual methods. The traced structures differ by up to 16 orders of magnitude in size, which demonstrates the universality of the tracing algorithm.

Authors: Markus J. Aschwanden, Bart De Pontieu, and Eugene A. Katrukha
Projects: None

Publication Status: Entropy, Special Issue on Advanced Signal Processing in Heliopspheric Physics, (in press)
Last Modified: 2013-07-18 18:46
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Nonlinear Force-Free Magnetic Field Fitting to Coronal Loops with and without Stereoscopy  

Markus J. Aschwanden   Submitted: 2012-12-12 14:51

We developed a new nonlinear force-free magnetic field (NLFFF) forward-fitting algorithm based on an analytical approximation of force-free and divergence-free NLFFF solutions, which requires as input a line-of-sight magnetogram and traced 2D loop coordinates of coronal loops only, in contrast to stereoscopically triangulated 3D loop coordinates used in previous studies. Test results of simulated magnetic configurations and from four active regions observed with STEREO demonstrate that NLFFF solutions can be fitted with equal accuracy with or without stereoscopy, which relinquishes the necessity of STEREO data for magnetic modeling of active regions (on the solar disk). The 2D loop tracing method achieves a 2D misalignment of mu_2=2.7°pm 1.3° between the model field lines and observed loops, and an accuracy of approx 1.0% for the magnetic energy or free magnetic energy ratio. The three times higher spatial resolution of TRACE or SDO/AIA (compared with STEREO) yields also a proportionally smaller misalignment angle between model fit and observations. Visual/manual loop tracings are found to produce more accurate magnetic model fits than automated tracing algorithms. The computation time of the new forward-fitting code amounts to a few minutes per active region.

Authors: Markus J. Aschwanden
Projects: STEREO

Publication Status: (2013) The Astrophysical Journal 763, 115
Last Modified: 2014-03-25 16:30
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A Nonlinear Force-Free Magnetic Field Approximation Suitable for Fast Forward-Fitting to Coronal Loops III. The Free Energy  

Markus J. Aschwanden   Submitted: 2012-11-15 08:03

An analytical approximation of a nonlinear force-free magnetic field (NLFFF) solution was developed in Paper I, while a numerical code that performs fast forward-fitting of this NLFFF approximation to a line-of-sight magnetogram and coronal 3D loops has been described and tested in Paper II. Here we calculate the free magnetic energy E m free=E m N-E m P, ie the difference of the magnetic energies between the nonpotential field and the potential field. A second method to estimate the free energy is obtained from the mean misalignment angle change Deltamu=mu m P-mu m N between the potential and nonpotential field, which scales as E m free/E m P approx an^2{(Deltamu)}. For four active regions observed with STEREO in 2007 we find free energies in the range of q m free=(E m free/E m P) approx 1%-10%, with an uncertainty of less than pm 2% between the two methods, while the free energies obtained from 11 other NLFFF codes exhibit a larger scatter of order approxpm10%. We find also a correlation between the free magnetic energy and the GOES flux of the largest flare that occurred during the observing period, which can be quantified by an exponential relationship, F m GOES propto exp{(q m free/0.015)}, implying an exponentiation of the dissipated currents.

Authors: Markus J. Aschwanden
Projects: STEREO

Publication Status: Solar Physics (in press)
Last Modified: 2012-11-20 20:25
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The Spatio-Temporal Evolution of Solar Flare Observed with AIA/SDO: Fractal Diffusion, Sub-Diffusion, or Logistic Growth ?}  

Markus J. Aschwanden   Submitted: 2012-08-07 15:05

We explore the spatio-temporal evolution of solar flares by fitting a radial expansion model r(t) that consists of an exponentially growing acceleration phase, followed by a deceleration phase that is parameterized by the generalized diffusion function r(t) propto kappa (t-t_1)eta/2, which includes the logistic growth limit (eta=0), sub-diffusion (eta = 0-1), classical diffusion (eta=1), super-diffusion (eta = 1-2), and the linear expansion limit (eta=2). We analyze all M and X-class flares observed with GOES and AIA/SDO during the first two years of the SDO mission, amounting to 155 events. We find that most flares operate in the sub-diffusive regime (eta=0.53pm0.27), which we interpret in terms of anisotropic chain reactions of intermittent magnetic reconnection episodes in a low plasma-eta corona. We find a mean propagation speed of v=15pm12 km s-1, with maximum speeds of vmax=80 pm 85 km s-1 per flare, which is substantially slower than the sonic speeds expected for thermal diffusion of flare plasmas. The diffusive characteristics established here (for the first time for solar flares) is consistent with the fractal-diffusive self-organized criticality (FD-SOC) model, which predicted diffusive transport merely based on cellular automaton simulations.

Authors: Markus J. Aschwanden
Projects: SDO-AIA

Publication Status: ApJ Vol. 757, p.94 (2012)
Last Modified: 2012-09-11 13:42
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Self-Organized Criticality Systems in Astrophysics (Chapter 13)  

Markus J. Aschwanden   Submitted: 2012-07-18 10:41

Chapter 13: SOC Systems in Astrophysics -- Content list: 13.1 Theory - 13.1.1 The Sacle-Free Probability Theorem - 13.1.2 The Fractal-Diffusive Spatio-Temporal Relationship - 13.1.3 Size Distributions of Astrophysical Observables - 13.1.4 Scaling Laws for Thermal Emission of Astrophysical Plasmas - 13.1.5 Scaling Laws for Astrophysical Acceleration Mechanisms - 13.2 Observations - 13.2.1 Lunar Craters - 13.2.2 Asteroid Belt - 13.2.3 Saturn Ring - 13.2.4 Magnetospheric Substorms and Auroras - 13.2.5 Solar Flares - 13.2.6 Stellar Flares - 13.2.7 Pulsars - 13.2.8 Soft Gamma-Ray Repeaters - 13.2.9 Black-Hole Objects - 13.2.10 Blazars - 13.2.11 Cosmic Rays - 13.3 Conclusions

Authors: Markus J. Aschwanden
Projects:

Publication Status: e-book - Self-Organized Criticality Systems (subm. July 18, 2012)
Last Modified: 2012-07-18 13:11
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Solar Stereoscopy with STEREO/EUVI A and B spacecraft from small (6°) to large (170°) spacecraft separation angles  

Markus J. Aschwanden   Submitted: 2012-07-11 14:11

We performed for the first time stereoscopic triangulation of coronalloops in active regions over the entire range of spacecraft separationangles ( α sep≈ 6°, 43°, 89°, 127°,and 170°). The accuracy of stereoscopic correlation depends mostlyon the viewing angle with respect to the solar surface for eachspacecraft,which affects the stereoscopic correspondence identification of loops inimage pairs. From a simple theoretical model we predict an optimum rangeof α sep ≈ 22°-125°, which is also experimentallyconfirmed. The best accuracy is generally obtained when an active regionpasses the central meridian (viewed from Earth), which yields asymmetricview for both STEREO spacecraft and causes minimum horizontalforeshortening.For the extended angular range of α sep≈6°-127° wefind a mean 3D misalignment angle of μPF ≈ 21°-39°of stereoscopically triangulated loops with magnetic potential fieldmodels,and μFFF ≈ 15°-21° for a force-free field model,which is partly caused by stereoscopic uncertainties muSE ≈9°. We predict optimum conditions for solar stereoscopy duringthe timeintervals of 2012-2014, 2016-2017, and 2021-2023.

Authors: Markus J. Aschwanden, Jean-Pierre Wülser, Nariaki Nitta, and James Lemen
Projects: STEREO

Publication Status: Solar Physics (in press)
Last Modified: 2012-07-12 09:38
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First 3D Reconstructions of Coronal Loops with the STEREO A+B Spacecraft: IV. Magnetic Modeling with Twisted Force-Free Fields  

Markus J. Aschwanden   Submitted: 2012-07-11 14:09

The three-dimensional (3D) coordinates of stereoscopically triangulated loops provide strong constraints for magnetic field models of active regions in the solar corona. Here we use STEREO/A and B data from some 500 stereoscopically triangulated loops observed in four active regions (2007 Apr 30, May 9, May 19, Dec 11), together with SOHO/MDI line-of-sight magnetograms. We measure the average misalignment angle between the stereoscopic loops and theoretical magnetic field models, finding a mismatch of mu=19°-46° for a potential field model, which is reduced to mu=14°-19° for a non-potential field model parameterized by twist parameters. The residual error is commensurable with stereoscopic measurement errors (muSE approx 8°-12°). We developed a potential field code that deconvolves a line-of-sight magnetogram into three magnetic field components (B_x, B_y, B_z), as well as a non-potential field forward-fitting code that determines the full length of twisted loops (L approx 50-300 Mm), the number of twist turns (median Ntwist=0.06), the nonlinear force-free α -parameter (median α approx 4 imes 10-11 cm-1), and the current density (median j_z approx 1500 Mx cm-2 s-1). All twisted loops are found to be far below the critical value for kink instability, and Joule dissipation of their currents is found be be far below the coronal heating requirement. The algorithm developed here, based on an analytical solution of nonlinear force-free fields that is accurate to second order (in the force-free parameter α ), represents the first code that enables fast forward-fitting to photospheric magnetograms and stereoscopically triangulated loops in the solar corona.

Authors: Markus J. Aschwanden, Jean-Pierre Wuelser, Nariaki V. Nitta, James R. Lemen, Marc L. DeRosa, and Anna Malanushenko
Projects: STEREO

Publication Status: The Astrophysical Journal (in press)
Last Modified: 2012-07-12 09:38
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A Nonlinear Force-Free Magnetic Field Approximation Suitable for Fast Forward-Fitting to Coronal Loops. II. Numeric Code and Tests  

Markus J. Aschwanden   Submitted: 2012-07-11 14:05

Based on a second-order approximation of nonlinear force-free magnetic field solutions in terms of uniformly twisted field lines derived in Paper I, we develop here a numeric code that is capable to forward-fit such analytical solutions to arbitrary magnetogram (or vector magnetograph) data combined with (stereoscopically triangulated) coronal loop 3D coordinates. We test the code here by forward-fitting to six potential field and six nonpotential field cases simulated with our analytical model, as well as by forward-fitting to an exactly force-free solution of the Low and Lou (1990) model. The forward-fitting tests demonstrate: (i) a satisfactory convergence behavior (with typical misalignment angles of mu approx 1°-10°), (ii) relatively fast computation times (from seconds to a few minutes), and (iii) the high fidelity of retrieved force-free α -parameters ( α m fit α m model approx 0.9-1.0 for simulations and α m fit α m model approx 0.7pm0.3 for the Low and Lou model). The salient feature of this numeric code is the relatively fast computation of a quasi-forcefree magnetic field, which closely matches the geometry of coronal loops in active regions, and complements the existing {sl nonlinear force-free field (NLFFF)} codes based on photospheric magnetograms without coronal constraints.

Authors: Markus J. Aschwanden and Anna Malanushenko
Projects: STEREO

Publication Status: Solar Physics (in press)
Last Modified: 2012-07-12 09:38
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A Nonlinear Force-Free Magnetic Field Approximation Suitable for Fast Forward-Fitting to Coronal Loops. I. Theory  

Markus J. Aschwanden   Submitted: 2012-07-11 14:03

We derive an analytical approximation of nonlinear force-free magnetic field solutions (NLFFF) that can efficiently be used for fast forward-fitting to solar magnetic data, constrained either by observed line-of-sight magnetograms and stereoscopically triangulated coronal loops, or by 3D vector-magnetograph data. The derived NLFFF solutions provide the magnetic field components B_x({f x}), B_y({f x}), B_z({f x}), the force-free parameter α {f x}), the electric current density {f j}({f x}), and are accurate to second-order (of the nonlinear force-free α -parameter). The explicit expressions of a force-free field can easily be applied to modeling or forward-fitting of many coronal phenomena.

Authors: Markus J. Aschwanden
Projects: STEREO

Publication Status: Solar Physics (in press)
Last Modified: 2012-07-12 09:38
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Automated Solar Flare Statistics in Soft X-rays over 37 Years of GOES Observations - The Invariance of Self-Organized Criticality during Three Solar Cycles  

Markus J. Aschwanden   Submitted: 2012-05-30 08:52

We analyzed the soft X-ray light curves from the {sl Geostationary Operational Environmental Satellites (GOES)} over the last 37 years (1975-2011) and measured with an automated flare detection algorithm over 300,000 solar flare events (amounting to approx 5 times higher sensitivity than the NOAA flare catalog). We find a powerlaw slope of α _F=1.98pm0.11 for the (background-subtracted) soft X-ray peak fluxes that is invariant through three solar cycles and agrees with the theoretical prediction α _F=2.0 of the {sl fractal-diffusive self-organized criticality (FD-SOC)} model. For the soft X-ray flare rise times we find a powerlaw slope of α _T =2.02pm0.04 during solar cycle minima years, which is also consistent with the prediction α _T=2.0 of the FD-SOC model. During solar cycle maxima years, the powerlaw slope is steeper in the range of α _T approx 2.0-5.0, which can be modeled by a solar cycle-dependent flare pile-up bias effect. These results corroborate the FD-SOC model, which predicts a powerlaw slope of α _E=1.5 for flare energies and thus rules out significant nanoflare heating. While the FD-SOC model predicts the probability distribution functions of spatio-temporal scaling laws of nonlinear energy dissipation processes, additional physical models are needed to derive the scaling laws between the geometric SOC parameters and the observed emissivity in different wavelength regimes, as we derive here for soft X-ray emission. The FD-SOC model yields also statistical probabilities for solar flare forecasting.

Authors: Markus J. Aschwanden and Samuel L. Freeland
Projects: GOES X-rays

Publication Status: (2012) ApJ 754, 112
Last Modified: 2012-07-17 08:26
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Flares in the Crab Nebula Driven by Untwisting Magnetic Fields  

Markus J. Aschwanden   Submitted: 2012-04-30 15:35

The recent discovery of PeV electrons from the Crab nebula, produced on rapid time scales of one day or less with a sharply peaked gamma-ray spectrum without hard X-rays, challenges traditional models of diffusive shock acceleration followed by synchrotron radiation. Here we outline an accleration model involving a DC electric field parallel to the magnetic field in a twisted toroidal field around the pulsar. Sudden developments of resistivity in localized regions of the twisted field are thought to drive the particle acceleration, up to PeV energies, resulting in flares. This model can reproduce the observed time scales of T = 1 day, the peak photon energies of U_rr = 1 MeV, maximum electron energies of U_err = 1 PeV, and luminosities of L = 1036 erg/s.

Authors: Peter Sturrock and Markus J. Aschwanden
Projects: None

Publication Status: ApJ Lett. (accepted April 30, 2012; in press)
Last Modified: 2012-05-01 10:16
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GeV Particle Acceleration in Solar Flares and Ground Level Enhancement (GLE) Events  

Markus J. Aschwanden   Submitted: 2011-12-20 16:10

This abstract was corrupted following database problems and is being recovered. It will be restored as quickly as possible. Any questions, please send them to Alisdair. Sorry for any incovenience.


Authors: Markus J. Aschwanden
Projects: RHESSI

Publication Status: Space Science Reviews, Topical Issue on GLE, (accepted, 2011 Dec 20; in press)
Last Modified: 2011-12-21 12:17
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A Statistical Fractal-Diffusive Avalanche Model of a Slowly-Driven Self-Organized Criticality System  

Markus J. Aschwanden   Submitted: 2011-12-20 14:00

This abstract was corrupted following database problems and is being recovered. It will be restored as quickly as possible. Any questions, please send them to Alisdair. Sorry for any incovenience.


Authors: Markus J. Aschwanden
Projects: None

Publication Status: Astronomy and Astrophysics (accepted 2012 Dec 20; in press)
Last Modified: 2011-12-21 12:17
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Solar Stereoscopy with STEREO/EUVI A and B spacecraft from small (6 deg) to large (170 deg) spacecraft separation angles  

Markus J. Aschwanden   Submitted: 2011-10-25 15:13

This abstract was corrupted following database problems and is being recovered. It will be restored as quickly as possible. Any questions, please send them to Alisdair. Sorry for any incovenience.


Authors: Markus J. Aschwanden, Jean-Pierre Wuelser, Nariaki Nitta, James Lemen
Projects: None

Publication Status: Solar Physics, Sun-360 Topical issue (subm)
Last Modified: 2011-10-26 08:36
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First 3D Reconstructions of Coronal Loops with the STEREO A+B Spacecraft: IV. Magnetic Field Modeling with Uniformly Twisted Flux Tubes  

Markus J. Aschwanden   Submitted: 2011-10-25 15:10

This abstract was corrupted following database problems and is being recovered. It will be restored as quickly as possible. Any questions, please send them to Alisdair. Sorry for any incovenience.


Authors: Markus J. Aschwanden, Jean-Pierre Wuelser, Nariaki V. Nitta, James R. Lemen, Marc L. DeRosa, and Anna Malanushenko
Projects: STEREO

Publication Status: ApJ (subm)
Last Modified: 2011-10-26 08:36
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Coronal loop oscillations observed with AIA : Kink-mode with cross-sectional and density oscillation  

Markus J. Aschwanden   Submitted: 2011-05-11 12:34

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Authors: Aschwanden,M.J. and Schrijver,C.J.
Projects: SDO-AIA

Publication Status: ApJ 736, 102-121, (2011)
Last Modified: 2011-08-08 15:37
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Solar Corona Loop Studies with AIA: I. Cross-Sectional Temperature Structure  

Markus J. Aschwanden   Submitted: 2011-03-01 09:31

We present a first systematic study on the cross-sectional temperaturestructure of coronal loops using the six coronal temperature filtersof the Atmospheric Imaging Assembly (AIA) instrument on the SolarDynamics Observatory (SDO). We analyze a sample of 100 loop snapshotsmeasured at 10 different locations and 10 different times in activeregion NOAA 11089 on 2010 July 24, 21:00-22:00 UT. The cross-sectionalflux profiles are measured and a cospatial background is subtracted in6 filters in a temperature range of T ≈ 0.5-16 MK, and 4different parameterizations of differential emission measure (DEM)distributions are fitted. We find that the reconstructed DEMs consistpredominantly of narrowband peak temperature components with a thermalwidth of σlog(T) ≤ 0.11 ± 0.02,close to the temperature resolution limit of the instrument,consistent with earlier triple-filter analysis from TRACE byAschwanden and Nightingale (2005) and from EIS/Hinode by Warren et al.(2008) or Tripathi et al. (2009). We find that 66% of the loops couldbe fitted with a narrowband single-Gaussian DEM model, and 19% with aDEM consisting of two narrowband Gaussians (which mostly result frompairs of intersecting loops along the same line-of-sight). The mostlyisothermal loop DEMs allow us also to derive an improved empiricalresponse function of the AIA 94Å filter, which needs to be boostedby a factor of q94 = 6.7± 1.7 for temperaturesat log(T) ≤ 6.3. The main result of near-isothermal loopcross-sections is not consistent with the predictions of standardnanoflare scenarios, but can be explained by flare-like heatingmechanisms that drive chromospheric evaporation and upflows of heatedplasma coherently over loop cross-sections of w ≈ 2-4Mm.

Authors: Markus J. Aschwanden and Paul Boerner
Projects: SDO-AIA

Publication Status: ApJ (accepted March 1, 2011; in press)
Last Modified: 2011-03-01 18:50
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The State of Self-Organized Criticality of the Sun During the Last Three Solar Cycles. II. Theoretical Model  

Markus J. Aschwanden   Submitted: 2010-10-05 12:56

This abstract was corrupted following database problems and is being recovered. It will be restored as quickly as possible. Any questions, please send them to Alisdair. Sorry for any incovenience.


Authors: Markus J. Aschwanden
Projects: None

Publication Status: Solar Physics 274, 119-129, (2011)
Last Modified: 2012-01-12 12:05
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A Macroscopic Description of Self-Organized Criticality Systems and Astrophysical Applications
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Multi-Wavelength Observations of the Spatio-Temporal Evolution of Solar Flares with AIA/SDO:I. Universal Scaling Laws of Space and Time Parameters
Multi-Wavelength Observations of the Spatio-Temporal Evolution of Solar Flares with AIA/SDO:I. Universal Scaling Laws of Space and Time Parameters
Optimization of Curvi-Linear Tracing Applied to Solar Physics and Biophysics
Nonlinear Force-Free Magnetic Field Fitting to Coronal Loops with and without Stereoscopy
A Nonlinear Force-Free Magnetic Field Approximation Suitable for Fast Forward-Fitting to Coronal Loops III. The Free Energy
The Spatio-Temporal Evolution of Solar Flare Observed with AIA/SDO: Fractal Diffusion, Sub-Diffusion, or Logistic Growth ?}
Self-Organized Criticality Systems in Astrophysics (Chapter 13)
Solar Stereoscopy with STEREO/EUVI A and B spacecraft from small (6°) to large (170°) spacecraft separation angles
First 3D Reconstructions of Coronal Loops with the STEREO A+B Spacecraft: IV. Magnetic Modeling with Twisted Force-Free Fields
A Nonlinear Force-Free Magnetic Field Approximation Suitable for Fast Forward-Fitting to Coronal Loops. II. Numeric Code and Tests
A Nonlinear Force-Free Magnetic Field Approximation Suitable for Fast Forward-Fitting to Coronal Loops. I. Theory
Automated Solar Flare Statistics in Soft X-rays over 37 Years of GOES Observations - The Invariance of Self-Organized Criticality during Three Solar Cycles
Flares in the Crab Nebula Driven by Untwisting Magnetic Fields
GeV Particle Acceleration in Solar Flares and Ground Level Enhancement (GLE) Events
A Statistical Fractal-Diffusive Avalanche Model of a Slowly-Driven Self-Organized Criticality System
Solar Stereoscopy with STEREO/EUVI A and B spacecraft from small (6 deg) to large (170 deg) spacecraft separation angles
First 3D Reconstructions of Coronal Loops with the STEREO A+B Spacecraft: IV. Magnetic Field Modeling with Uniformly Twisted Flux Tubes
Coronal loop oscillations observed with AIA : Kink-mode with cross-sectional and density oscillation
Solar Corona Loop Studies with AIA: I. Cross-Sectional Temperature Structure
The State of Self-Organized Criticality of the Sun During the Last Three Solar Cycles. II. Theoretical Model
The State of Self-Organized Criticality of the Sun During the Last Three Solar Cycles. II. Theoretical Model
The State of Self-Organized Criticality of the Sun During the Last Three Solar Cycles. II. Theoretical Model
A Universal Scaling Law for the Fractal Energy Dissipation Domain in Self-Organized Criticality Systems
The State of Self-Organized Criticality of the Sun During the Last 3 Solar Cycles. I. Observations
The State of Self-Organized Criticality of the Sun During the Last 3 Solar Cycles. I. Observations
GeV Particle Acceleration in Solar Flares and Ground Level Enhancement (GLE) Events
Bootstrapping the coronal magnetic field with STEREO: I. Unipolar Potential Field Modeling
Self-Organized Criticality in Solar Physics and Astrophysics
3D Reconstruction of Active Regions with STEREO (Invited Review)
Reconciliation of waiting time statistics of solar flares observed in hard X-rays
A Code for Automated Tracing of Coronal Loops Approaching Visual Perception
4D-Modeling of CME Expansion and EUV Dimming Observed with STEREO/EUVI
First Measurements of the Mass of Coronal Mass Ejections from the EUV Dimming Observed with STEREO EUVI A+B Spacecraft
The 3D Geometry, 3D Motion, and Hydrodynamics of Oscillating Coronal Loops
Hydrodynamic Modeling of Coronal Loops with Hinode and STEREO
First 3D Reconstructions of Coronal Loops with the STEREO A+B Spacecraft: III. Instant Stereoscopic Tomography of Active Regions
Solar Flare and CME Observations with STEREO/EUVI
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The Effect of Radiative Cooling on Coronal Loop Oscillations
New Aspects on Particle Acceleration in Solar Flares from RHESSI Observations
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An Observational Test That Disproves Coronal Nanoflare Heating Models
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Solar Flare Geometries. II. The Volume Fractal Dimension
Comparison of Five Numerical Codes for Automated Tracing of Coronal Loops
ASTROPHYSICS IN 2006
Solar Flare Physics Enlivened by TRACE and RHESSI (Invited)
Keynote Address: Outstanding Problems in Solar Physics
Scaling Laws for Solar and Stellar Flares
From Solar Nanoflares to Stellar Giant Flares - Scaling Laws and Non-Implications for Coronal Heating
Solar Flare Geometries. I. The Area Fractal Dimension
The Coronal Heating Paradox
Theoretical Modeling for the STEREO Mission
The Localization of Particle Acceleration Sites in Solar Flares and CMEs
Three Criteria to Discriminate Between Elementary and Composite Coronal Loops
Elementary Loop Structures in the Solar Corona Analyzed from TRACE Triple-Filter Images

Related Pages
MSU Solar Physics.
Max Millennium Science Mail Archive.
Max Millennium Message of the Day Mail Archive.
Max Millennium Flare Catalog

Archive Maintainer
Alisdair Davey



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