Dynamic Models of Optical Emission in Impulsive Solar Flares

Abbett, W. P.; Hawley, Suzanne L.

doi:10.1086/307576

Cited by 177 publications

(234 citation statements)

References 34 publications

Supporting

Mentioning

223

Contrasting

Unclassified

Order By: Relevance

“…It is unlikely that the time delay in the early stage is thermal in nature. According to Abbett & Hawley (1999), in the presence of nonthermal beams, as evidenced by HXR emission, the thermal inÑuence on the chromosphere is negligible.…”

Section: Discussionmentioning

confidence: 99%

“…The heating and ionization of the chromosphere by nonthermal electrons can produce optical (e.g., Ha) emission nearly simultaneously with hard X-ray bursts (CanÐeld, Gunkler, & Ricchiazzi 1984 ;Fisher, CanÐeld, & McClymont 1985 ;CanÐeld & Gayley 1987 ;Hawley & Fisher 1994 ;Abbett & Hawley 1999). SpeciÐcally, the emission in the wing of the Ha line may be produced via Stark broadening by electrons moving down to the deep chromosphere (e.g., Svestka 1976).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

High‐Cadence Observations of an Impulsive Flare

Wang¹,

Qiu²,

Denker³

et al. 2000

ApJ

View full text Add to dashboard Cite

We analyzed high-cadence observations of a C5.7 Ñare on 1999 August 23 at Big Bear Solar Observatory (BBSO). The observing wavelength was 1.3 in the blue wing of Ha, with a cadence of 0.033 s. In A addition, the hard X-rayÏs time proÐle obtained by the Burst And Transient Source Experiment (BATSE) and BBSO high-resolution magnetograms was compared with our Ha observations to understand in detail the particle precipitation in this event. The important results are as follows :three Ñare kernels were observed in the early phase of the Ñare. The Ñare started in a A , nonmagnetic area at the magnetic neutral line. This suggests to us that the top of a low-lying loop is the initial energy release site, while the other two kernels are the footpoints of another overlying Ñare loop, formed after the magnetic reconnection.2. We analyzed the temporal behavior of the three Ñare kernels in the impulsive phase when hard X-ray (HXR) emission was signiÐcant. We found that during a 7 s period, the Ha[1.3 brightenings at A one of the footpoints showed a very good temporal correlation with the HXR Ñux variation. Therefore, from the spatially resolved Ha o †-band observations, we identiÐed this Ñare kernel as the source of HXR emission.3. From the footpoint which exhibits the best correlation with HXR emission, the Ha[1.3 emission A shows high-frequency Ñuctuations on a timescale of a few tenths of a second. The amplitude of the Ñuc-tuations is more than 3 times the noise. Such Ñuctuations are not evident in the other Ñare kernels which also do not show good correlation with HXR emission. For this reason, we suggest that the observed high-frequency Ñuctuations may be signatures of temporal Ðne structure related to the HXR elementary bursts.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

High‐Cadence Observations of an Impulsive Flare

Wang¹,

Qiu²,

Denker³

et al. 2000

ApJ

View full text Add to dashboard Cite

show abstract

“…We perform radiative hydrodynamic modeling using code RADYN with application to solar flares as described in detail in Abbett (1999). The infrared triplet of neutral helium is considered.…”

Section: Methodsmentioning

confidence: 99%

“…The nonthermal electron beam is assumed to have a power-law distribution with a spectral index of δ = 5 and low energy cutoff of E c = 40 keV. More simulation details see Abbett (1999).…”

Section: Methodsmentioning

confidence: 99%

Radiative Hydrodynamic Simulations of He I 10830 Å

Cheng¹,

Ding

Fang

2012

Proc. IAU

View full text Add to dashboard Cite

Abstract. We study the properties of the He I 10830Å line under the bombardment of nonthermal electron beam. Using radiative hydrodynamics method, we obtain the line profiles from different model atmospheres by varying the electron beam fluxes. Below a certain electron flux, the spectra become much more absorptions as nonthemal flux increases. Above the threshold, the spectral intensities increase as the flux goes up. We also investigate the temporal evolution of the spectra under the nonthermal heating. For weak electron flux, the profiles evolve from weak absorptions to strong absorptions. For strong nonthermal heating, the profiles can be significantly changed from absorptions to emissions. The spectra also show red or blue asymmetries.

show abstract

“…The values for quiet sun conditions were calculated from the initial data profile used in the code GOEMHD3D (Skála et al 2015). The values for the flaring atmosphere were obtained from the results of numerical simulations of Abbett & Hawley (1999). In the dense and collisional plasma of the chromosphere the ratio λ mfp /L T is within the limit allowing the SH thermal conductivity.…”

Section: Introductionmentioning

confidence: 99%

Nonlocal heat flux effects on temperature evolution of the solar atmosphere

Silva

Santos

Büchner

et al. 2018

A&A

View full text Add to dashboard Cite

Context. Heat flux is one of the main energy transport mechanisms in the weakly collisional plasma of the solar corona. There, rare binary collisions let hot electrons travel over long distances and influence other regions along magnetic field lines. Thus, the fully collisional heat flux models might not describe transport well enough since they consider only the local contribution of electrons. The heat flux in weakly collisional plasmas at high temperatures with large mean free paths has to consider the nonlocality of the energy transport in the frame of nonlocal models in order to treat energy balance in the solar atmosphere properly. Aims. We investigate the impact of nonlocal heat flux on the thermal evolution and dynamics of the solar atmosphere by implementing a nonlocal heat flux model in a 3D magnetohydrodynamic simulation of the solar corona. Methods. We simulate the evolution of solar coronal plasma and magnetic fields considering both a local collision dominated and a nonlocal heat flux model. The initial magnetic field is obtained by a potential extrapolation of the observed line-of-sight magnetic field of AR11226. The system is perturbed by moving the plasma at the photosphere. We compared the simulated evolution of the solar atmosphere in its dependence on the heat flux model. Results. The main differences for the average temperature profiles were found in the upper chromosphere/transition region. In the nonlocal heat transport model case, thermal energy is transported more efficiently to the upper chromosphere and lower transition region and leads to an earlier heating of the lower atmosphere. As a consequence, the structure of the solar atmosphere is affected with the nonlocal simulations producing on average a smoother temperature profile and the transition region placed about 500 km higher. Using a nonlocal heat flux also leads to two times higher temperatures in some of the regions in the lower corona. Conclusions. The results of our 3D MHD simulations considering nonlocal heat transport supports the previous results of simpler 1D two-fluid simulations. They demonstrated that it is important to consider a nonlocal formulation for the heat flux when there is a strong energy deposit, like the one observed during flares, in the solar corona.

show abstract

Dynamic Models of Optical Emission in Impulsive Solar Flares

Cited by 177 publications

References 34 publications

High‐Cadence Observations of an Impulsive Flare

High‐Cadence Observations of an Impulsive Flare

Radiative Hydrodynamic Simulations of He I 10830 Å

Nonlocal heat flux effects on temperature evolution of the solar atmosphere

Contact Info

Product

Resources

About