SolO/EUI Observations of Ubiquitous Fine-scale Bright Dots in an Emerging Flux Region: Comparison with a Bifrost MHD Simulation

Tiwari, Sanjiv K.; Hansteen, V. H.; Pontieu, Bart De; Panesar, Navdeep K.; Berghmans, D.

doi:10.3847/1538-4357/ac5d46

Cited by 11 publications

(14 citation statements)

References 112 publications

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“…These jets are of short duration and less than half the length of jets reported in another study based on Hi-C observations by Panesar et al (2019) where the jets had their origin due to photospheric magnetic flux cancellation. These nanojets are of about less than half the length but are of similar widths when compared with microjets observations by Hou et al (2021) and jet-like campfires and EUV dots reported by Panesar et al (2021) and Tiwari et al (2022), respectively, using the Solar Orbiter EUI data. The lifetime of the observed nanojets is on average smaller than the small-scale jet-like features in aforementioned studies.…”

Section: Conclusion and Discussionsupporting

confidence: 78%

Hi-C 2.1 Observations of Reconnection Nanojets

Patel

Pant

2022

ApJ

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One of the possible mechanisms for heating the solar atmosphere is the magnetic reconnection occurring at different spatiotemporal scales. The discovery of fast bursty nanojets due to reconnection in the coronal loops has been linked to nanoflares and is considered as a possible mechanism for coronal heating. The occurrence of these jets mostly in the direction inwards to the loop was observed in the past. In this study, we report 10 reconnection nanojets, four with directions inward and six moving outward to the loop, in observations from the High-resolution Coronal Imager 2.1 and the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory. We determined the maximum length, spire width, speed, and lifetimes of these jets and studied their correlations. We found that outward jets with higher speeds are longer in length and duration while the inward jets show opposite behavior. The average duration of the outward jets is ≈42 s and that of inward jets is ≈24 s. We identified jets with subsonic speeds below 100 km s−1 to high speeds over 150 km s−1. These jets can be identified in multiple passbands of AIA extending from the upper transition region to the corona suggesting their multithermal nature.

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Section: Conclusion and Discussionsupporting

confidence: 78%

Hi-C 2.1 Observations of Reconnection Nanojets

Patel

Pant

2022

ApJ

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“…These observations were made as a part of a technical compression test of HRI EUV , therefore having variable settings. Nonetheless, 60 images are well exposed, unbinned, and compressed at high-quality levels (Panesar et al 2021;Tiwari et al 2022). The HRI EUV events appear 3.22 minutes earlier than the SDO/AIA images because, as mentioned, the Solar Orbiter was closer to the Sun than the SDO.…”

Section: Solar Orbiter/euimentioning

confidence: 89%

“…They occur at the edges of quiet Sun network regions and are driven by the eruption of cool plasma structures. Further, there are several other campfire-like events that were observed by HRI EUV e.g., fine-scale dots in an emerging region (Tiwari et al 2022), plasma jets (Chitta et al 2021), and plasma flows (Mandal et al 2021;Li 2022).…”

Section: Introductionmentioning

confidence: 97%

Solar Orbiter and SDO Observations, and a Bifrost Magnetohydrodynamic Simulation of Small-scale Coronal Jets

Panesar

Hansteen

Tiwari

et al. 2023

ApJ

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We report high-resolution, high-cadence observations of five small-scale coronal jets in an on-disk quiet Sun region observed with Solar Orbiter’s EUI/HRIEUV in 174 Å. We combine the HRIEUV images with the EUV images of SDO/AIA and investigate the magnetic setting of the jets using coaligned line-of-sight magnetograms from SDO/HMI. The HRIEUV jets are miniature versions of typical coronal jets as they show narrow collimated spires with a base brightening. Three out of five jets result from a detectable minifilament eruption following flux cancelation at the neutral line under the minifilament, analogous to coronal jets. To better understand the physics of jets, we also analyze five small-scale jets from a high-resolution Bifrost MHD simulation in synthetic Fe ix/Fe x emissions. The jets in the simulation reside above neutral lines and four out of five jets are triggered by magnetic flux cancelation. The temperature maps show evidence of cool gas in the same four jets. Our simulation also shows the signatures of opposite Doppler shifts (of the order of ±10 s of km s−1) in the jet spire, which is evidence of untwisting motion of the magnetic field in the jet spire. The average jet duration, spire length, base width, and speed in our observations (and in synthetic Fe ix/Fe x images) are 6.5 ± 4.0 min (9.0 ± 4.0 minutes), 6050 ± 2900 km (6500 ± 6500 km), 2200 ± 850 km, (3900 ± 2100 km), and 60 ± 8 km s−1 (42 ± 20 km s−1), respectively. Our observation and simulation results provide a unified picture of small-scale solar coronal jets driven by magnetic reconnection accompanying flux cancelation. This picture also aligns well with the most recent reports of the formation and eruption mechanisms of larger coronal jets.

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“…Furthermore, Berghmans et al (2021) pointed out that the reconnection responsible for campfires appears at the apexes of intersected loops; nevertheless, our results show that it more likely occurs at the legs of loops. Very recently, Tiwari et al (2022) even found some very tiny dot-like EUV brightenings, part of which were identified to be caused by reconnection at a lower height. In short, we support the argument that, despite a shorter duration, the campfires belong to the flare family and that the corresponding scale resides between microflares and nanoflares.…”

Section: Summary and Discussionmentioning

confidence: 99%

Three-dimensional Magnetic and Thermodynamic Structures of Solar Microflares

Cheng

Chen

et al. 2022

ApJL

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Microflares, one of the small-scale solar activities, are believed to be caused by magnetic reconnection. Nevertheless, their three-dimensional (3D) magnetic structures, thermodynamic structures, and physical links to reconnection are unclear. In this Letter, based on a high-resolution 3D radiative magnetohydrodynamic simulation of the quiet Sun spanning from the upper convection zone to the corona, we investigate the 3D magnetic and thermodynamic structures of three homologous microflares. It is found that they originate from localized hot plasma embedded in the chromospheric environment at the height of 2–10 Mm above the photosphere and last for 3–10 minutes with released magnetic energy in the range of 1027–1028 erg. The heated plasma is almost cospatial with the regions where the heating rate per particle is maximal. The 3D velocity field reveals a pair of converging flows with velocities of tens of km s−1 moving toward and outflows with velocities of about 100 km s−1 moving away from the hot plasma. These features support magnetic reconnection playing a critical role in heating the localized chromospheric plasma to coronal temperature, giving rise to the observed microflares. The magnetic topology analysis further discloses that the reconnection region is located near quasi-separators where both current density and squashing factors are maximal although the specific topology may vary from a tether-cutting to fan-spine-like structure.

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SolO/EUI Observations of Ubiquitous Fine-scale Bright Dots in an Emerging Flux Region: Comparison with a Bifrost MHD Simulation

Cited by 11 publications

References 112 publications

Hi-C 2.1 Observations of Reconnection Nanojets

Hi-C 2.1 Observations of Reconnection Nanojets

Solar Orbiter and SDO Observations, and a Bifrost Magnetohydrodynamic Simulation of Small-scale Coronal Jets

Three-dimensional Magnetic and Thermodynamic Structures of Solar Microflares

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