Two-phase Heating in Flaring Loops

Zhu, Chunming; Qiu, Jiong; Longcope, D. W.

doi:10.3847/1538-4357/aaad10

Cited by 35 publications

(43 citation statements)

References 62 publications

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“…Nevertheless, due to the possible non-equilibrium ionization at flare temperatures early in the long tenuous late-phase loop, the bump is absent in the observed AIA 335Å light curve. Recently, Zhu et al (2018) studied a C-class two-ribbon solar flare using the EBTEL model, in which the modeled peaks in AIA 131 and 94Å are also well above the observed peaks (Figure 3 in their paper).…”

Section: Comparison With Observationsmentioning

confidence: 86%

“…During a solar flare, the optically thin C IV lines are significantly enhanced, showing a prompt and sensitive response to the flare energy release. Therefore, the evolution in AIA 1600Å can be regarded as a proxy for flare heating Qiu et al 2012;Zhu et al 2018). The AIA 1600Å intensity profile of the AR (purple) shown in Figure 3(e) reveals two peaks at 12:42:41 and 12:47:53 UT (highlighted by the vertical dashed lines), respectively, indicative of two main episodes of energy release taking place in quick succession.…”

Section: Two-stage Energy Releasementioning

confidence: 99%

“…To infer the heating function for the loop, we calculate the chromospheric light curve at the loop footpoint, as proposed by Li et al (2012), Qiu et al (2012), and Zhu et al (2018). To this end, we draw a 6 ′′ × 6 ′′ box (Box 1 in Figure 6) at the eastern footpoint of the selected late-phase loop, which is located on the remote flare ribbon R1.…”

Section: Comparison With Observationsmentioning

confidence: 99%

See 2 more Smart Citations

Extremely Large Extreme-ultraviolet Late Phase Powered by Intense Early Heating in a Non-eruptive Solar Flare

Dai

Ding

Zong

et al. 2018

ApJ

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We analyzed and modeled an M1.2 non-eruptive solar flare on 2011 September 9. The flare exhibits a strong late-phase peak of the warm coronal emissions (∼3 MK) of extreme-ultraviolet (EUV), with peak emission over 1.3 times that of the main flare peak. Multiple flare ribbons are observed, whose evolution indicates a two-stage energy release process. A non-linear force-free field (NLFFF) extrapolation reveals the existence of a magnetic null point, a fan-spine structure, and two flux ropes embedded in the fan dome. Magnetic reconnections involved in the flare are driven by the destabilization and rise of one of the flux ropes. In the first stage, the fast ascending flux rope drives reconnections at the null point and the surrounding quasi-separatrix layer (QSL), while in the second stage, reconnection mainly occurs between the two legs of the field lines stretched by the eventually stopped flux rope. The late-phase loops are mainly produced by the first-stage QSL reconnection, while the second-stage reconnection is responsible for the heating of main flaring loops. The first-stage reconnection is believed to be more powerful, leading to an extremely strong EUV late phase. We find that the delayed occurrence of the late-phase peak is mainly due to the long cooling process of the long late-phase loops. Using the model enthalpy-based thermal evolution of loops (EBTEL), we model the EUV emissions from a late-phase loop. The modeling reveals a peak heating rate of 1.1 erg cm −3 s −1 for the late-phase loop, which is obviously higher than previous values.

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Section: Comparison With Observationsmentioning

confidence: 86%

Section: Two-stage Energy Releasementioning

confidence: 99%

Section: Comparison With Observationsmentioning

confidence: 99%

See 1 more Smart Citation

Extremely Large Extreme-ultraviolet Late Phase Powered by Intense Early Heating in a Non-eruptive Solar Flare

Dai

Ding

Zong

et al. 2018

ApJ

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show abstract

“…In fact, a recent study by Kuhar et al (2017) has shown that the energy released during the gradual phase is at least an order of magnitude larger than the energy released during the impulsive phase. Models of on-going reconnection have been shown to be compatible with the late-phase properties of flares (Cargill & Priest 1983), and multi-threaded modeling of post-flare loops have been able to reproduce long duration light curves observed with GOES and SDO/AIA (Li et al 2014;Qiu & Longcope 2016;Zhu et al 2018).…”

Section: Discussionmentioning

confidence: 99%

What Determines the X-Ray Intensity and Duration of a Solar Flare?

Reep

Knizhnik

2019

ApJ

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Solar flares are observed and classified according to their intensity measured with the GOES X-ray Sensors. We show that the duration of a flare, as measured by the full width at half maximum (FWHM) in GOES is not related to the size of the flare as measured by GOES intensity. The durations of X-class flares range from a few minutes to a few hours, and the same is true of M-and C-class flares. In this work, we therefore examine the statistical relationships between the basic properties of flares -temperature, emission measure, energy, etc. -in comparison to both their size and duration. We find that the size of the flare is directly related to all of these basic properties, as previously found by many authors. The duration is not so clear. When examining the whole data set, the duration appears to be independent of all of these properties. In larger flares, however, there are direct correlations between the GOES FWHM and magnetic reconnection flux and ribbon area. We discuss the possible explanations, finding that this discrepancy may be due to large uncertainties in small flares, though we cannot rule out the possibility that the driving physical processes are different in smaller flares than larger ones. We discuss the implications of this result and how it relates to the magnetic reconnection process that releases energy in flares.

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“…Therefore, magnetic reconnection, which occurs in the corona yet can be hardly measured there, is mapped in the lower atmosphere by flare radiation, and the reconnection rate is measured by summing up photospheric magnetic fluxes covered by spreading flare ribbons. This method has been widely used to measure the magnetic reconnection rate (e.g., Qiu et al 2002Qiu et al , 2004Isobe et al 2002;Asai et al 2004;Krucker et al 2005;Miklenic et al 2007;Veronig & Polanec 2015;Kazachenko et al 2017;Zhu et al 2018). In this study, the brightening pixels are collected from AIA imaging observations in 1600Å or 304Å passband to measure the reconnection rate in flares ranging from X-class to B-class.…”

Section: Measurement Of Reconnection Propertiesmentioning

confidence: 99%

How Does Magnetic Reconnection Drive the Early-stage Evolution of Coronal Mass Ejections?

Zhu

Qiu

Liewer

et al. 2020

ApJ

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Theoretically, CME kinematics are related to magnetic reconnection processes in the solar corona. However, the current quantitative understanding of this relationship is based on the analysis of only a handful of events. Here we report a statistical study of 60 CME-flare events from August 2010 to December 2013. We investigate kinematic properties of CMEs and magnetic reconnection in the low corona during the early phase of the eruptions, by combining limb observations from STEREO with simultaneous on-disk views from SDO. For a subset of 42 events with reconnection rate evaluated by the magnetic fluxes swept by the flare ribbons on the solar disk observed from SDO, we find a strong correlation between the peak CME acceleration and the peak reconnection rate. Also, the maximum velocities of relatively fast CMEs ( 600 km s −1 ) are positively correlated with the reconnection flux, but no such correlation is found for slow CMEs. A time-lagged correlation analysis suggests that the distribution of the time lag of CME acceleration relative to reconnection rate exhibits three peaks, approximately 10 minutes apart, and on average, acceleration-lead events have smaller reconnection rates. We further compare the CME total mechanical energy with the estimated energy in the current sheet. The comparison suggests that, for small-flare events, reconnection in the current sheet alone is insufficient to fuel CMEs. Results from this study suggest that flare reconnection may dominate

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Two-phase Heating in Flaring Loops

Cited by 35 publications

References 62 publications

Extremely Large Extreme-ultraviolet Late Phase Powered by Intense Early Heating in a Non-eruptive Solar Flare

Extremely Large Extreme-ultraviolet Late Phase Powered by Intense Early Heating in a Non-eruptive Solar Flare

What Determines the X-Ray Intensity and Duration of a Solar Flare?

How Does Magnetic Reconnection Drive the Early-stage Evolution of Coronal Mass Ejections?

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