Fine-scale Explosive Energy Release at Sites of Prospective Magnetic Flux Cancellation in the Core of the Solar Active Region Observed by Hi-C 2.1, IRIS, and SDO

Tiwari, Sanjiv K.; Panesar, Navdeep K.; Moore, Ronald L.; Pontieu, Bart De; Winebarger, Amy R.; Golub, L.; Savage, Sabrina; Rachmeler, Laurel; Kobayashi, K.; Testa, Paola; Warren, H. P.; Brooks, David H.; Cirtain, Jonathan; McKenzie, D. E.; Morton, Richard; Peter, Hardi; Walsh, R. W.

doi:10.3847/1538-4357/ab54c1

Cited by 53 publications

(68 citation statements)

References 92 publications

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“…So, our results demonstrate that, in cancelling regions, a wide spectrum of ejections can be produced, with a wide range of different temperatures and sizes associated with Ellerman bombs, UV bursts and IRIS bombs and other hot and cool ejections (Yang et al 2013;Vissers et al 2015;Reid et al 2016;Rutten 2016;Nelson et al 2017;Rouppe van der Voort et al 2017;Young et al 2018;Tian et al 2018;Chen et al 2019;Guglielmino et al 2019;Ortiz et al 2020;Tiwari et al 2019;Huang et al 2019;Madjarska 2019). The predicted spatial offsets and time delays for hot and cool ejections are in accordance with observational findings.…”

Section: Discussionsupporting

confidence: 88%

A Cancellation Nanoflare Model for Solar Chromospheric and Coronal Heating. III. 3D Simulations and Atmospheric Response

Syntelis

Priest

2020

ApJ

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Inspired by recent observations suggesting that photospheric magnetic flux cancellation occurs much more frequently than previously thought, we analytically estimated the energy released from reconnection driven by photospheric flux cancellation, and proposed that it can act as a mechanism for chromospheric and coronal heating (Priest et al. 2018). Using two-dimensional simulations we validated the analytical estimates and studied the resulting atmospheric response (Syntelis et al. 2019). In the present work, we set up three-dimensional resistive MHD simulations of two cancelling polarities in a stratified atmosphere with a horizontal external field to further validate and improve upon the analytical estimates. The computational evaluation of the parameters associated with the energy release are in good qualitative agreement with the analytical estimates. The computational Poynting energy flux into the current sheet is in good qualitative agreement with the analytical estimates, after correcting the analytical expression to better account for the horizontal extent of the current sheet. The atmospheric response to the cancellation is the formation of hot ejections, cool ejections, or a combination of both hot and cool ejections, which can appear with a time difference and/or be spatially offset, depending on the properties of the cancelling region and the resulting height of the reconnection. Therefore, during the cancellation, a wide spectrum of ejections can be formed, which can account for the variety of multi-thermal ejections associated with Ellerman bombs, UV bursts and IRIS bombs, and also other ejections associated with small-scale cancelling regions and spicules.

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Section: Discussionsupporting

confidence: 88%

A Cancellation Nanoflare Model for Solar Chromospheric and Coronal Heating. III. 3D Simulations and Atmospheric Response

Syntelis

Priest

2020

ApJ

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“…Furthermore, the magnetic set-up of campfires are also similar to the magnetic environment of small-scale events (e.g. jetlets, explosive events, and coronal bright points) that are also seen to occur due to flux cancelation (e.g., Panesar et al 2018bPanesar et al , 2019Tiwari et al 2019;Madjarska 2019).…”

Section: Magnetic Field Evolution At Campfire's Basementioning

confidence: 85%

“…The average lengths of the campfires are smaller than the average lengths of Hi-C 2.1 jet-like events (Panesar et al 2020a) and EUI microjets (Hou et al 2021). The sizes of dot-like campfires are similar or smaller than the sizes of Hi-C 2.1 dot-like events (Tiwari et al 2019). The majority of campfires (40) have durations of less than 10 minutes.…”

Section: Statistical Physical Propertiesmentioning

confidence: 94%

The Magnetic Origin of Solar Campfires

Panesar,

Tiwari,

Berghmans

et al. 2021

Preprint

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Solar campfires are fine-scale heating events, recently observed by Extreme Ultraviolet Imager (EUI), onboard Solar Orbiter. Here we use EUI 174Å images, together with EUV images from SDO/AIA, and line-of-sight magnetograms from SDO/HMI to investigate the magnetic origin of 52 randomly selected campfires in the quiet solar corona. We find that (i) the campfires are rooted at the edges of photospheric magnetic network lanes; (ii) most of the campfires reside above the neutral line between majority-polarity magnetic flux patch and a merging minority-polarity flux patch, with a flux cancelation rate of ∼10 18 Mx hr −1 ; (iii) some of the campfires occur repeatedly from the same neutral line; (iv) in the large majority of instances, campfires are preceded by a cool-plasma structure, analogous to minifilaments in coronal jets; and (v) although many campfires have 'complex' structure, most campfires resemble small-scale jets, dots, or loops. Thus, 'campfire' is a general term that includes different types of small-scale solar dynamic features. They contain sufficient magnetic energy (∼10 26 -10 27 erg) to heat the solar atmosphere locally to 0.5-2.5MK. Their lifetimes range from about a minute to over an hour, with most of the campfires having a lifetime of <10 minutes. The average lengths and widths of the campfires are 5400±2500km and 1600±640km, respectively. Our observations suggest that (a) the presence of magnetic flux ropes may be ubiquitous in the solar atmosphere and not limited to coronal jets and larger-scale eruptions that make CMEs, and (b) magnetic flux cancelation is the fundamental process for the formation and triggering of most campfires.

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“…The interpretation of the small jets is based on cartoons showing magnetic reconnection in mixed local magnetic field polarities. The spectra at the reconnection site show bidirectional flows either in the low chromosphere (Joshi et al, 2021b), in the corona (Ruan et al, 2019), or at the top of an emergent minifilament (Tiwari et al, 2019). Large Doppler flows can be found at the reconnection, for example, around +/-100-200 km/s (Joshi et al, 2021b).…”

Section: Rotating Structurementioning

confidence: 95%

“…Cool jets or surges show also such blue/red Dopplershifts parallel to the structure (Figure 7A) (Tian et al, 2014;Ruan et al, 2019). Blue and red shift pattern is not always interpreted as a possible rotation (Schmieder et al, 1983;Tiwari et al, 2019), However, frequently, it is defined that the characteristics of the twisting jet is relatively common and does not depend on the temperature or the coronal environment. Twisting has been found in penumbra jets (Tiwari et al, 2018), and in active region jets (Lu et al, 2019;Joshi et al, 2021b) using Si IV, C II, and Mg II lines observed by the IRIS.…”

Section: Rotating Structurementioning

confidence: 99%

Solar Jets: SDO and IRIS Observations in the Perspective of New MHD Simulations

Schmieder

2022

Front. Astron. Space Sci.

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Solar jets are observed as collimated plasma beams over a large range of temperatures and wavelengths. They have been observed in H α and optical lines for more than 50 years and called surges. The term “jet” comes from X-ray observations after the launch of the Yohkoh satellite in 1991. They are the means of transporting energy through the heliosphere and participate to the corona heating and the acceleration of solar wind. Several characteristics have been derived about their velocities, their rates of occurrence, and their relationship with CMEs. However, the initiation mechanism of jets, e.g. emerging flux, flux cancellation, or twist, is still debated. In the last decade coordinated observations of the Interface Region Imaging Spectrograph (IRIS) with the instruments on board the Solar Dynamic Observatory (SDO) allow to make a step forward for understanding the trigger of jets and the relationship between hot jets and cool surges. We observe at the same time the development of 2D and 3D MHD numerical simulations to interpret the results. This paper summarizes recent studies of jets showing the loci of magnetic reconnection in null points or in bald patch regions forming a current sheet. In the pre-jet phase a twist is frequently detected by the existence of a mini filament close to the dome of emerging flux. The twist can also be transferred to the jet from a flux rope in the vicinity of the reconnection by slippage of the polarities. Bidirectional flows are detected at the reconnection sites. We show the role of magnetic currents detected in the footprints of flux rope and quasi-separatrix layers for initiating the jets. We select a few studies and show that with the same observations, different interpretations are possible based on different approaches e.g. non linear force free field extrapolation or 3D MHD simulation.

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Fine-scale Explosive Energy Release at Sites of Prospective Magnetic Flux Cancellation in the Core of the Solar Active Region Observed by Hi-C 2.1, IRIS, and SDO

Cited by 53 publications

References 92 publications

A Cancellation Nanoflare Model for Solar Chromospheric and Coronal Heating. III. 3D Simulations and Atmospheric Response

A Cancellation Nanoflare Model for Solar Chromospheric and Coronal Heating. III. 3D Simulations and Atmospheric Response

The Magnetic Origin of Solar Campfires

Solar Jets: SDO and IRIS Observations in the Perspective of New MHD Simulations

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