Chromospheric evaporation in sympathetic coronal bright points

Zhang, Q. M.; Ji, Haisheng

doi:10.1051/0004-6361/201321908

Cited by 32 publications

(32 citation statements)

References 55 publications

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“…It is expected that jets can occur across the full range of L/N. Reported values range from 2.5 to 4 in large-scale jets (e.g., Sun et al 2013;Cheung et al 2015) to 5 and higher in small-scale jets (e.g., Zhang & Ji 2013;Zhang et al 2016). Over the parameter range studied in WD16, the threshold for triggering the kink instability that led to the jet, as well as the subsequent jet dynamics, were found to depend strongly on the ratio L/N.…”

Section: Jet Modelmentioning

confidence: 99%

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Three-Dimensional Simulations of Tearing and Intermittency in Coronal Jets

Wyper

DeVore

Karpen

et al. 2016

ApJ

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Observations of coronal jets increasingly suggest that local fragmentation and intermittency play an important role in the dynamics of these events. In this work, we investigate this fragmentation in high-resolution simulations of jets in the closed-field corona. We study two realizations of the embedded-bipole model, whereby impulsive helical outflows are driven by reconnection between twisted and untwisted field across the domed fan plane of a magnetic null. We find that the reconnection region fragments following the onset of a tearing-like instability, producing multiple magnetic null points and flux-rope structures within the current layer. The flux ropes formed within the weak-field region in the center of the current layer are associated with "blobs" of density enhancement that become filamentary threads as the flux ropes are ejected from the layer, whereupon new flux ropes form behind them. This repeated formation and ejection of flux ropes provides a natural explanation for the intermittent outflows, bright blobs of emission, and filamentary structure observed in some jets. Additional observational signatures of this process are discussed. Essentially all jet models invoke reconnection between regions of locally closed and locally open field as the jet-generation mechanism. Therefore, we suggest that this repeated tearing process should occur at the separatrix surface between the two flux systems in all jets. A schematic picture of tearing-mediated jet reconnection in three dimensions is outlined.

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Section: Jet Modelmentioning

confidence: 99%

“…In these cases, the jet material propagates along the ambient coronal loops and the spire often has a curved appearance. Closed-field jets also have been associated with brightening at the distant footpoint of the connecting coronal loop (e.g., Török et al 2009;Zhang & Ji 2013).…”

Section: Introductionmentioning

confidence: 99%

Three-Dimensional Simulations of Tearing and Intermittency in Coronal Jets

Wyper

DeVore

Karpen

et al. 2016

ApJ

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“…From 22:49 UT on August 22 to 01:29 UT on August 23, the CBP experienced two flashes and presented interesting structures. We focus on this time span and divide it into a weak-flash phase (from 22:49 UT on August 22 to 00:40 UT on August 23) and a strong-flash phase (00:40−01:29 UT on August 23), during which the CBP induced a sympathetic CBP and gentle chromospheric evaporations within it (Zhang & Ji 2013). Since alternative brightening of two patches was observed inside the CBP, it is more appropriate to call it a CBP complex, rather than a simple one.…”

Section: Observation and Data Analysismentioning

confidence: 99%

“…The point-like or loop-like bright features are widely distributed in the quiet regions and in coronal holes (Habbal et al 1990;Kotoku et al 2007;Madjarska & Wiegelmann 2009;Zhang & Ji 2013). The temperature and density of CBPs are typically 1−3 MK and 10 9 −10 10 cm −3 (Ugarte- Urra et al 2005;Kariyappa et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Reciprocatory magnetic reconnection in a coronal bright point

Zhang

Chen

Ding

et al. 2014

A&A

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Context. Coronal bright points (CBPs) are small-scale and long-duration brightenings in the lower solar corona. They are often explained in terms of magnetic reconnection. Aims. We aim to study the substructures of a CBP and clarify the relationship among the brightenings of different patches inside the CBP. Methods. The event was observed by the X-ray Telescope (XRT) aboard the Hinode spacecraft on 2009 August 22−23. Results. The CBP showed repeated brightenings (or CBP flashes). During each of the two successive CBP flashes, that is, weak and strong flashes that were separated by ∼2 hr, the XRT images revealed that the CBP was composed of two chambers, patches A and B. During the weak flash, patch A brightened first, and patch B brightened ∼2 min later. During the transition, the right leg of a large-scale coronal loop drifted from the right side of the CBP to the left side. During the strong flash, patch B brightened first, and patch A brightened ∼2 min later. During the transition, the right leg of the large-scale coronal loop drifted from the left side of the CBP to the right side. In each flash, the rapid change of the connectivity of the large-scale coronal loop is strongly suggestive of the interchange reconnection. Conclusions. For the first time we found reciprocatory reconnection in the CBP, which means that reconnected loops in the outflow region of the first reconnection process serve as the inflow of the second reconnection process.

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“…It is widely accepted that coronal jets are heated by magnetic reconnection between emerging flux and the pre-existing magnetic fields with opposite polarity (Shibata & Uchida 1986;Yokoyama & Shibata 1996;Moreno-Insertis et al 2008;Török et al 2009;Moreno-Insertis & Galsgaard 2013). According to the numerical simulations of Yokoyama & Shibata (1996), there are hot, compact microflares at their footpoints (Krucker et al 2011;Zhang & Ji 2013) and cool Hα surges adjacent to the hot jets (Schmieder et al 1995;Canfield et al 1996;Liu & Kurokawa 2004;Jiang et al 2007;Liu 2008;Nelson & Doyle 2013). The EUV emissions from a hot jet were observed to be absorbed by the foreground cool surge, which resulted in EUV dimming behind the leading edge of the jet (Zhang & Ji 2014).…”

Section: Introductionmentioning

confidence: 99%

Blobs in recurring extreme-ultraviolet jets

Zhang

2014

A&A

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Context. Coronal jets are one type of ubiquitous small-scale activity that is caused by magnetic reconnection in the solar corona. They are often associated with cool surges in the chromosphere. Aims. In this paper, we report our discovery of blobs in the recurrent and homologous jets that occurred at the western edge of the NOAA active region 11259 on 2011 July 22. Methods. The jets were observed in the seven extreme-ultraviolet (EUV) filters of the Atmospheric Imaging Assembly instrument aboard the Solar Dynamics Observatory. Using the base-difference images of the six filters (94, 131, 171, 211, 193, and 335 Å), we carried out the differential emission measure (DEM) analyses to explore the thermodynamic evolutions of the jets. The jets were accompanied by cool surges observed in the Hα line center of the ground-based telescope in the Big Bear Solar Observatory. Results. The jets that had lifetimes of 20−30 min recurred at the same place for three times with an interval of 40−45 min. Interestingly, each of the jets intermittently experienced several upward eruptions at the speed of 120−450 km s −1 . After reaching the maximum heights, they returned back to the solar surface, showing near-parabolic trajectories. The falling phases were more evident in the low-T filters than in the high-T filters, indicating that the jets experienced cooling after the onset of eruptions. We identified bright and compact blobs in the jets during their rising phases. The simultaneous presence of blobs in all the EUV filters were consistent with the broad ranges of the DEM profiles of the blobs (5.5 ≤ log T ≤ 7.5), indicating their multi-thermal nature. The median temperatures of the blobs were ∼2.3 MK. The blobs that were ∼3 Mm in diameter had lifetimes of 24−60 s. Conclusions. To our knowledge, this is the first report of blobs in coronal jets. We propose that these blobs are plasmoids created by the magnetic reconnection as a result of tearing-mode instability and are ejected out along the jets.

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Chromospheric evaporation in sympathetic coronal bright points

Cited by 32 publications

References 55 publications

Three-Dimensional Simulations of Tearing and Intermittency in Coronal Jets

Three-Dimensional Simulations of Tearing and Intermittency in Coronal Jets

Reciprocatory magnetic reconnection in a coronal bright point

Blobs in recurring extreme-ultraviolet jets

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