Plasma Heating in the Very Early and Decay Phases of Solar Flares

Falewicz, R.; Siarkowski, M.; Rudawy, P.

doi:10.1088/0004-637x/733/1/37

Cited by 15 publications

(31 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Spectral analysis to investigate the likelihood that the higher energy photons (and a significant fraction of the lower energy X-ray photons in the first peak) were from nonthermal electrons was inconclusive because of the low level of emission above 12 keV and the uncertainty in the background subtraction. Despite RHESSI's observation of no hard X-ray emission before 5:16 UT, nonthermal electrons could still have provided the power input required to heat the chromospheric plasma at these earlier times (e.g., Siarkowski et al 2009;Falewicz et al 2011). …”

Section: Based On Aia and Cdsmentioning

confidence: 99%

Using SDO’s AIA to investigate energy transport from a flare’s energy release site to the chromosphere

Brosius

Holman

2012

A&A

View full text Add to dashboard Cite

Context. Coordinated observations of a GOES B4.8 microflare with SDO's Atmospheric Imaging Assembly (AIA) and the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) on 2010 July 31 show that emission in all seven of AIA's EUV channels brightened simultaneously nearly 6 min before RHESSI or GOES detected emission from plasma at temperatures around 10 MK. Aims. To help interpret these and AIA flare observations in general, we characterized the expected temporal responses of AIA 's 94, 131, 171, 193, 211, and 335 Å channels to solar flare brightenings by combining (1) AIA's nominal temperature response functions available through SSWIDL with (2) EUV spectral line data observed in a flare loop footpoint on 2001 April 24 with the Coronal Diagnostic Spectrometer (CDS) on timescales comparable to AIA's image cadence. Methods. The nine emission lines observed by CDS cover a wide range of formation temperature from about 0.05 to 8 MK. Line brightenings observed early during the CDS flare occurred at temperatures less than about 0.7 MK, with the largest values around 0.1 MK. These brightenings were consistent with the flare's energy transport being dominated by nonthermal particle beams. Because all of AIA's EUV channels are sensitive to emission from plasma in the 0.1 to 0.7 MK temperature range, we show that all of AIA's EUV channels will brighten simultaneously during flares like this, in which energy transport is dominated by nonthermal particle beams. Results. The 2010 July 31 flare observed by AIA and RHESSI displays this behavior, so we conclude that such beams likely dominated the flare's energy transport early during the event. When thermal conduction from a reconnection-heated, hot (∼10 MK) plasma dominates the energy transport, the AIA channels that are sensitive to emission from such temperatures (particularly the 94 and 131 Å channels) will brighten earlier than the channels that are not sensitive to such temperatures (171 and 211 Å). Conclusions. Thus, based on the differences expected between AIA's response to flares whose energy transport is dominated by nonthermal particle beams from those whose energy transport is dominated by thermal conduction, AIA can be used to determine the dominant energy transport mechanism for any given event.

show abstract

Section: Based On Aia and Cdsmentioning

confidence: 99%

Using SDO’s AIA to investigate energy transport from a flare’s energy release site to the chromosphere

Brosius

Holman

2012

A&A

View full text Add to dashboard Cite

show abstract

“…In this paper we used all achievements of our previous investigations of the energy transfer and deposition processes in simple, single-loop solar flares, in particular our investigations of interactions of the non-thermal electrons with matter (Falewicz, Rudawy, & Siarkowski 2009a,b;Falewicz, Siarkowski, & Rudawy 2011;Siarkowski, Falewicz, & Rudawy 2009) and numerical modelling of the X-ray flare emission (Falewicz, Rudawy, & Siarkowski 2009b;Falewicz, Siarkowski, & Rudawy 2011). Additionally, in our work we took into account the results presented by Liu, Petrosian, & Mariska (2009), which validated certain simplifications during the modelling of solar flares, and were helpful in the interpretation of the results.…”

Section: Introductionmentioning

confidence: 99%

Plasma Heating in Solar Flares and Their Soft and Hard X-Ray Emissions

Falewicz

2014

ApJ

Self Cite

View full text Add to dashboard Cite

In this paper, the energy budgets of two single-loop like flares observed in X-ray are analysed under the assumption that non-thermal electrons (NTEs) are the only source of plasma heating during all phases of both events. The flares were observed by RHESSI and GOES on February 20 th , 2002 and June 2 nd , 2002, respectively. Using a 1D hydrodynamic code for both flares the energy deposited in the chromosphere was derived applying RHESSI observational data. The use of the Fokker-Planck formalism permits the calculation of distributions of the non-thermal electrons in flaring loops, thus spatial distributions of the X-ray non-thermal emissions and integral fluxes for the selected energy ranges which were compared with the observed ones. Additionally, a comparative analysis of the spatial distributions of the signals in the RHESSI images was conducted for the footpoints and for the entire flare loops in selected energy ranges with these quantities fluxes obtained from the models. The best compatibility of the model and observations was obtained for the June 2 nd , 2002 event in the 0.5-4 Å GOES range and total fluxes in the 6-12 keV, 12-25 keV, 20-25 keV and 50-100 keV energy bands. Results of photometry of the individual flaring structures in a high energy range shows that the best compliance occurred for the June 2 nd , 2002 flare, where the synthesized emissions were 30% or more higher than the observed emissions. For the February 20 th , 2002 flare, synthesized emission is about 4 times lower than the observed one. However, in the low energy range the best conformity was obtained for the February 20 th , 2002 flare, where emission from the model is about 11% lower than the observed one. The larger inconsistency occurs for the June 2 nd , 2002 solar flare, where synthesized emission is about 12 times greater or even more than the observed emission. Some part of these differences may be caused by inevitable flaws of the applied methodology, like by an assumption that the model of the flare is symmetric and there are no differences in the emissions originating from the feet of the flares loop and by relative simplicity of the applied numerical 1D code and procedures. No doubt a significant refinement of the applied numerical models and more sophisticated implementation of the various physical mechanisms involved are required to achieve

show abstract

“…He showed that modelling a flare as a sequence of independently heated threads instead of as a single loop may resolve the discrepancies between the simulations and observations, but by cost of some ad-hoc parameters (number of loops, energy share by particular loops etc.). Additionally, Falewicz et al (2011) andFalewicz (2014) showed that energy delivered by non-thermal electrons was fully sufficient to fulfill the energy budgets of the plasma during the pre-heating and impulsive phases of analyzed flares as well as during the decay phase. They concluded that in the case of the investigated flares there was no need to use any additional heating mechanisms other than heating by NTEs.…”

Section: Discussionmentioning

confidence: 99%

“…Such diversity of the position of the energy deposition volumes reflects various parameters of the NTEs beams, particularly various hardness of the NTEs energy spectra. The actual positions of the energy deposition volume, applied in each model are selected so that they overlap the position of the energy deposition region which is estimated with the use of the 1D HD model of a flare (see Falewicz et al, 2011). Thus, synthetic fluxes calculated in any spectral domain for the investigated flare could not be similar to real fluxes recorded for any real solar event, including also the progenitor flare.…”

Section: Introductionmentioning

confidence: 99%

2d MHD and 1d Hd Models of a Solar Flare—a Comprehensive Comparison of the Results

Falewicz

Rudawy

Murawski³

et al. 2015

ApJ

Self Cite

View full text Add to dashboard Cite

Without any doubt solar flaring loops possess a multi-thread internal structure that is poorly resolved and there are no means to observe heating episodes and thermodynamic evolution of the individual threads. These limitations cause fundamental problems in numerical modelling of flaring loops, such as selection of a structure and a number of threads, and an implementation of a proper model of the energy deposition process. A set of 1D hydrodynamic and 2D magnetohydrodynamic models of a flaring loop are developed to compare energy redistribution and plasma dynamics in the course of a prototypical solar flare. Basic parameters of the modeled loop are set according to the progenitor M1.8 flare recorded in the AR10126 on September 20, 2002 between 09:21 UT and 09:50 UT. The non-ideal 1D models include thermal conduction and radiative losses of the optically thin plasma as energy loss mechanisms, while the non-ideal 2D models take into account viscosity and thermal conduction as energy loss mechanisms only. The 2D models have a continuous distribution of the parameters of the plasma across the loop, and are powered by varying in time and space along and across the loop heating flux. We show that such 2D models are a borderline case of a multi-thread internal structure of the flaring loop, with a filling factor equal to one. Despite the assumptions used in applied 2D models, their overall success in replicating the observations suggests that they can be adopted as a correct approximation of the observed flaring structures.

show abstract

Plasma Heating in the Very Early and Decay Phases of Solar Flares

Cited by 15 publications

References 42 publications

Using SDO’s AIA to investigate energy transport from a flare’s energy release site to the chromosphere

Using SDO’s AIA to investigate energy transport from a flare’s energy release site to the chromosphere

Plasma Heating in Solar Flares and Their Soft and Hard X-Ray Emissions

2d MHD and 1d Hd Models of a Solar Flare—a Comprehensive Comparison of the Results

Contact Info

Product

Resources

About