Coronal Microjets in Quiet-Sun Regions Observed with the Extreme Ultraviolet Imager on Board the Solar Orbiter

Hou, Zhenyong; Berghmans, David; Chen, Hechao; Teriaca, L.; Schühle, U.; Gao, Yuhang; Chen, Yajie; He, Jiansen; Wang, Linghua; Bai, Xianyong

doi:10.3847/2041-8213/ac1f30

Cited by 32 publications

(42 citation statements)

References 113 publications

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“…The loop-like campfires also look similar to the low-lying loop nanoflare events in the moss region observed by Hi-C (Winebarger et al 2013). The sizes of our jet-like campfires are smaller than the sizes of Hi-C 2.1 jet-like events (Panesar et al 2019) and EUI microjets (Hou et al 2021). Further, these two studies did not find any evidence of cool-plasma structure at the jet-base regions.…”

Section: Discussionsupporting

confidence: 75%

“…The sizes of these events are evidently larger than the spatial resolution of the HRI EUV data (∼400 km). 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).…”

Section: Statistical Physical Propertiesmentioning

confidence: 88%

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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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Section: Discussionsupporting

confidence: 75%

Section: Statistical Physical Propertiesmentioning

confidence: 88%

The Magnetic Origin of Solar Campfires

Panesar,

Tiwari,

Berghmans

et al. 2021

Preprint

Self Cite

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“…Moreover, it is shown that two Si iv line profiles show obvious redshifts, which could be caused by the downflows from the reconnection region around the transition region. Similar observations were found in the transition region explosive events around the footpoints of network jets (Chen et al 2019;Hou et al 2021). Naturally, one may wonder why the TB detected here did not produce a jet.…”

Section: Tb Versus Ijsupporting

confidence: 82%

Various Activities above Sunspot Light Bridges in IRIS Observations: Classification and Comparison

Hou,

Li,

Yang

et al. 2022

Preprint

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Light bridges (LBs) are among the most striking sub-structures in sunspots, where various activities have been revealed by recent high-resolution observations from the Interface Region Imaging Spectrograph (IRIS ). According to the variety of physical properties, we classified these activities into four distinct categories: transient brightening (TB), intermittent jet (IJ), type-I light wall (LW-I), and type-II light wall (LW-II). In IRIS 1400/1330 Å observations, TBs are characterized by abrupt emission enhancements, and IJs appear as collimated plasma ejections with a width of 1-2 Mm at some LB sites. Most observed TBs are associated with IJs and show superpositions of some chromosphere absorption lines on enhanced and broadened wings of C ii and Si iv lines, which could be driven by intermittent magnetic reconnection in the lower atmosphere. LW-I and LW-II are wall-shaped structures with bright fronts above the whole LB. An LW-I has a continuous oscillating front with a typical height of several Mm and an almost stationary period of 4-5 minutes. On the contrary, an LW-II has a indented front with a height of over 10 Mm, which has no stable period and is accompanied by recurrent TBs in the entire LB. These results support that LW-IIs are driven by frequent reconnection occurring along the whole LB due to large-scale magnetic flux emergence or intrusion, rather than the leakage of waves producing LW-Is. Our observations reveal a highly dynamical scenario of activities above LBs driven by different basic physical processes, including magneto-convection, magnetic reconnection, and wave leakage.

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“…Therefore, we need to know how the scale size spectrum of coronal jets extends down to these small-scale sub-arcsecond material ejections when high-resolution observations are available (Raouafi et al 2016;Hou et al 2021). We also need to know the behaviors of all above-mentioned microeruptions in high-resolution He I 10830 Å imaging observations.…”

Section: Introductionmentioning

confidence: 99%

Quasi-periodic microjets driven by granular advection as observed with high-resolution imaging at He I 10830 Å

Hong,

Wang,

2022

Preprint

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With high-resolution narrowband He I 10830 Å filtergrams from GST, we give an extensive analysis for 4 granular sized microeruptions which appear as the gentle ejection of material in He I 10830 Å band. The analysis was aided with the EUV data from AIA and line-of-sight magnetograms from HMI on board SDO. The microeruptions are situated on magnetic polarity inversion lines (PILs), and their roots are accurately traced down to intergranular lanes. Their durations are different, two microeruptions are repetitive microjets, lasting ∼ 50 and 27 minutes respectively, while the other two events are singular, lasting ∼ 5 minutes. For the two microjets, they are continuous and recurrent in He I 10830 Å band, and the recurrence is quasi-periodic with the period of ∼ 5 minutes. We found that only transient co-spatial EUV brightenings are observed for the longer duration microjets and EUV brightenings are absent for the two singular microeruptions. What is essential to the longer duration microjets is that granules with the concentration of positive magnetic field persistently transport the magnetic field to the PILs, canceling the opposite magnetic flux and making the base of the two microjets and the underlying granules migrate with the speed of ∼ 0.25 and 1.0 km s −1 . The observations support the scenario of magnetic reconnection for the quasi-periodic microjets and further show that the reconnection continuously generates multi-temperature components, especially the cool component with chromospheric temperature. In addition, the ongoing reconnection is modulated by p-mode oscillations inside the Sun.

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Coronal Microjets in Quiet-Sun Regions Observed with the Extreme Ultraviolet Imager on Board the Solar Orbiter

Cited by 32 publications

References 113 publications

The Magnetic Origin of Solar Campfires

The Magnetic Origin of Solar Campfires

Various Activities above Sunspot Light Bridges in IRIS Observations: Classification and Comparison

Quasi-periodic microjets driven by granular advection as observed with high-resolution imaging at He I 10830 Å

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