Post-flare coronal loop interaction

We analyze multi-wavelength data of a M7.9/1N class solar flare which occurred on 27 April, 2006 from AR NOAA 10875. GOES soft X-ray images provide the most likely signature of two interacting loops and their reconnection, which triggers the solar flare. TRACE 195Å images also reveal the loop-loop interaction and the formation of 'X' points with converging motion (∼30 km s −1 ) at the reconnection site in-between this interacting loop system. This provides the evidence of progressive reconnection and flare maximization at the interaction site in the active region. The absence of type III radio burst during this time period indicates no opening of magnetic field lines during the flare energy release, which implies only the change of field lines connectivity/orientation during the loop-loop interaction and reconnection process. The Ondrejov dynamic radio spectrum shows an intense decimetric (DCIM) radio burst (2.5-4.5 GHz, duration∼3 min) during flare initiation, which reveals the signature of particle acceleration from the reconnection site during loop-loop interaction. The double peak structures at 4.9 and 8.8 GHz provide the most likely confirmatory signature of the loop-loop interaction at the flare site in the active region. RHESSI hard X-ray images also show the loop-top and footpoint sources of the corresponding two loop system and their coalescence during the flare maximum, which act like the current carrying flux-tubes with resultant opposite magnetic fields and the net force of attraction. We also suggest that the shear motion/rotation of the footpoint of the smaller loop, which is anchored in the opposite polarity spot, may be responsible for the flare energy buildup and then its release due to the loop-loop interaction.

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“…We can estimate the amount of energy (E c ) available due to coalescence instability (Tajima et al 1982;Smartt et al 1993) by:…”

Section: Some Theoretical Estimationsmentioning

confidence: 99%

Evidence of Solar Flare Triggering Due to Loop-Loop Interaction Caused by Footpoint Shear Motion

Kumar

Srivastava

Сомов

et al. 2010

ApJ

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“…It occurs under various conditions, in both quiet and dynamic environments. Reconnection has been observed throughout the heliosphere, including the solar corona (Smartt et al 1993;Xue et al 2016) and solar wind (Gosling et al 2005;Fargette et al 2021;Phan et al 2020). Near Earth, the magnetosphere provides a highly accessible natural laboratory for detailed measurements of reconnection events, which have been recently made by the Magnetospheric Multiscale (MMS) mission , Lavraud et al 2016Russell et al 2017) Reconnection can couple multiple scales (Hesse & Cassak 2020).…”

Section: Introductionmentioning

confidence: 99%

Magnetic Flux Transport Identification of Active Reconnection: MMS Observations in Earth’s Magnetosphere

Russell

et al. 2022

ApJL

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Magnetic reconnection plays an important role in converting energy while modifying field topology. This process takes place under varied plasma conditions during which the transport of magnetic flux is intrinsic. Identifying active magnetic reconnection sites with in situ observations is challenging. A new technique, Magnetic Flux Transport (MFT) analysis, has been developed recently and proven in numerical simulation for identifying active reconnection efficiently and accurately. In this study, we examine the MFT process in 37 previously reported electron diffusion region (EDR)/reconnection-line crossing events at the day-side magnetopause and in the magnetotail and turbulent magnetosheath using Magnetospheric Multiscale measurements. The coexisting inward and outward MFT flows at an X-point provides a signature that magnetic field lines become disconnected and reconnected. The application of MFT analysis to in-situ observations demonstrates that MFT can successfully identify active reconnection sites under complex varied conditions, including asymmetric and turbulent upstream conditions. It also provides a higher rate of identification than plasma outflow jets alone. MFT can be applied to in situ measurements from both single- and multi-spacecraft missions and laboratory experiments.

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“…Impulsive heating and sudden local release of energy leading to high temperature effects and transient brightenings are possibly the signature of this mechanism, (see, e.g. Smartt, Zhang and Smutko, 1993;Wood et al, 1998). We will not consider this process in this paper simply because it presumably requires good spatial resolution observations which are difficult to obtain simultaneously with precise spectroscopic data, especially from the ground.…”

Section: Introductionmentioning

confidence: 99%

Analysis of non-thermal velocities in the solar corona

Contesse¹,

Koutchmy²,

Viladrich³

2004

Ann. Geophys.

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Abstract. We describe new ground-based spectroscopic observations made using a 40-cm aperture coronagraph over a whole range of radial distances (up to heights of 12 above the limb) and along four different heliocentric directions N, E, S and W. The analysis is limited to the study of the brightest forbidden emission line of Fe XIV at 530.3 nm, in order to reach the best possible signal-to-noise ratio. To make the results statistically more significant, the extracted parameters are averaged over the whole length of the slit, and measurements are repeated fives times at each position; the corresponding dispersions in the results obtained along the slit are given. Central line profile intensities and full line widths (FWHM) are plotted and compared to measurements published by other authors closer to the limb. We found widths and turbulent (non-thermal) velocities of significantly higher values above the polar regions, especially when a coronal hole is present along the line of sight. We do not see a definitely decreasing behaviour of widths and turbulent velocities in equatorial directions for larger radial distances, as reported in the literature, although lower values are measured compared to the values in polar regions. The variation in the high corona is rather flat and a correlation diagram indicates that it is different for different regions and different radial distances. This seems to be the first analysis of the profiles of this coronal line, up to large heights above the limb for both equatorial and polar regions.

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Post-flare coronal loop interaction

Cited by 25 publications

References 25 publications

Evidence of Solar Flare Triggering Due to Loop-Loop Interaction Caused by Footpoint Shear Motion

Evidence of Solar Flare Triggering Due to Loop-Loop Interaction Caused by Footpoint Shear Motion

Magnetic Flux Transport Identification of Active Reconnection: MMS Observations in Earth’s Magnetosphere

Analysis of non-thermal velocities in the solar corona

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