Clear Evidence of Reconnection Inflow of a Solar Flare

Yokoyama, T.; Akita, Kazuo; Morimoto, Taro; Inoue, Kazuaki; Newmark, Jeffrey

doi:10.1086/318053

Cited by 317 publications

(254 citation statements)

References 12 publications

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“…Reconnection inflow with an apparent speed of 5 km s −1 and a plasmoid ejection could be detected during a flare by SXT and EIT (Yokoyama et al 2001).…”

Section: Flaresmentioning

confidence: 96%

Observations of the Sun at Vacuum-Ultraviolet Wavelengths from Space. Part II: Results and Interpretations

et al. 2007

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In Part I of this review, the concepts of solar vacuum-ultraviolet (VUV) observations were outlined together with a discussion of the space instrumentation used for the investigations. A section on spectroradiometry provided some quantitative results on the solar VUV radiation without considering any details of the solar phenomena leading to the radiation. Here, in Part II, we present solar VUV observations over the last decades and their interpretations in terms of the plasma processes and the parameters of the solar atmosphere, with emphasis on the spatial and thermal structures of the chromosphere, transition region and corona of the quiet Sun. In addition, observations of active regions, solar flares and prominences are included as well as of small-scale events. Special sections are devoted to the elemental composition of the solar atmosphere and theoretical considerations on the heating of the corona and the generation of the solar wind.

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“…Reconnection inflow with an apparent speed of 5 km s −1 and a plasmoid ejection could be detected during a flare by SXT and EIT (Yokoyama et al 2001).…”

Section: Flaresmentioning

confidence: 96%

Observations of the Sun at Vacuum-Ultraviolet Wavelengths from Space. Part II: Results and Interpretations

et al. 2007

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“…However, the reconnection rate in the solar atmosphere has rarely been addressed, because of the difficulty in determining inflow and outflow speeds from remote-sensing observation. Nevertheless, the presence of reconnection inflow in the solar atmosphere was inferred from the two approaching legs of a cusp-shaped structure by some authors (Yokoyama et al 2001;Lin et al 2005). However, approaching legs may be caused by the relaxation of the reconnected closed loop rather than a reconnection inflow, if the observation slit is not placed exactly across the x-point.…”

Section: Introductionmentioning

confidence: 99%

Reconfiguration of the coronal magnetic field by means of reconnection driven by photospheric magnetic flux convergence

He¹,

Marsch²,

Tu³

et al. 2010

A&A

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Context. Magnetic reconnection is commonly believed to be responsible for flare-like events and plasma ejections in the solar atmosphere, but the field-line reconfiguration observed in association with magnetic reconnection has rarely been observed before. Aims. We attempt to reconstruct the configuration of the magnetic field during a magnetic reconnection event, estimate the reconnection rate, and analyze the resulting X-ray burst and plasma ejection. Methods. We use the local-correlation-tracking (LCT) method to track the convergence of magnetic fields with opposite polarities using photospheric observations from SOT/Hinode. The magnetic field lines are then extrapolated from the tracked footpoint positions into the corona, and the changes in field-line connections are marked. We estimate the reconnection rate by calculating the convective electric field in the photosphere, which is normalized to the product of the plasma jet speed and the coronal magnetic field strength inside the inflow region. The observed X-ray burst and plasma ejection are analysed with data from XRT/Hinode and TRACE, respectively. Results. We find that in this reconnection event the two sets of approaching closed loops were reconfigured to a set of superimposed large-scale closed loops and another set of small-scale closed loops. Enhanced soft X-ray emission was seen to rapidly fill the reconnected loop after the micro-flare occurred at the reconnection site. Plasma was ejected from that site with a speed between 27 and 40 km s −1 . The reconnection rate is estimated to range between 0.03 and 0.09. Conclusions. Our work presents a study of the magnetic field reconfiguration owing to magnetic reconnection driven by flux convergence in the photosphere. This observation of the magnetic structure change is helpful for future diagnosis of magnetic reconnection. The results obtained for the reconnection rate, the X-ray emission burst, and the plasma ejection provides new observational evidence, and places constraints on future theoretical study of magnetic reconnection in the Sun.

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“…In particular, some of the clearest evidence for this process is in the occurence and subsequent dynamics of a solar flare (e.g. Yokoyama et al 2001). The evolution/expansion of bright flare loops following an eruption are an indication of magnetic reconnection continuing in the corona (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Flare loop arcades have been studied extensively from either theoretical (Sturrock 1968;Kopp & Pneuman 1976;Yokoyama & Shibata 1998) or observational (McKenzie & Hudson 1999;Yokoyama et al 2001;Isobe et al 2002) perspectives or both (Forbes & Acton 1996). There are various models for the magnetic reconnection process itself which differ in their estimation of the reconnection rate in two spatial dimensions (e.g.…”

Section: Introductionmentioning

confidence: 99%

Indirect calculation of the magnetic reconnection rate from flare loops

Noglik¹,

Walsh²,

Ireland

2005

A&A

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Abstract. High time resolution Transition Region And Coronal Explorer (TRACE) 171 and 195 Å observations of the evolution of flare loops on 1999 March 18 have been investigated. Given the location of the magnetic loops on the northeast solar limb and the cadence of the TRACE observations (∼50 s), an estimation of the footpoint velocity due to ongoing reconnection was undertaken. This was achieved by calculating the velocity at which successive loops brighten in the emission lines during the postflare phase. A typical footpoint velocity of 1.5 km s −1 ± 0.7 km s −1 is obtained and a reconnection rate of ∼0.001−0.03 is determined using the method outlined in Isobe et al. (2002, ApJ, 566, 528). This value for the reconnection rate is consistent with the regime outlined by Petschek's model for magnetic reconnection.

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Clear Evidence of Reconnection Inflow of a Solar Flare

Cited by 317 publications

References 12 publications

Observations of the Sun at Vacuum-Ultraviolet Wavelengths from Space. Part II: Results and Interpretations

Observations of the Sun at Vacuum-Ultraviolet Wavelengths from Space. Part II: Results and Interpretations

Reconfiguration of the coronal magnetic field by means of reconnection driven by photospheric magnetic flux convergence

Indirect calculation of the magnetic reconnection rate from flare loops

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