Magnetic reconnection in partially ionized plasmas

Ni, Lei; Ji, Hantao; Murphy, N. A.; Jara-Almonte, Jonathan

doi:10.1098/rspa.2019.0867

Cited by 37 publications

(29 citation statements)

References 219 publications

(455 reference statements)

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“…The blob-like features observed here are likely manifestations of plasmoids, and thus the large thickness of the plasma sheet or current sheet might be caused by a similar process. Such blobs are frequently seen in numerical simulations of magnetic reconnection involving plasmoid instability in the non-flaring solar atmosphere (e.g., Ni et al 2015Ni et al , 2020Ni et al , 2021Peter et al 2019). We noticed that similar moving blob-like features within current sheets or along newly formed loops have been previously reported from observations of flares (e.g., Takasao et al 2012Takasao et al , 2016Tian et al 2014;Cheng et al 2018;Huang et al 2018;Gou et al 2019;Mishra et al 2020), filament eruptions (e.g., Li et al 2016;Chen et al 2019a;Xue et al 2020b), chromospheric jets (e.g., Yan et al 2015) and coronal jets (e.g., Zhang & Ni 2019).…”

Section: Discussionmentioning

confidence: 95%

Formation of solar coronal loops through magnetic reconnection in an emerging active region

Hou¹,

Chen²,

Zhu³

et al. 2021

Preprint

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Coronal loops are building blocks of solar active regions (ARs). However, their formation is not well understood. Here we present direct observational evidence for the formation of coronal loops through magnetic reconnection as new magnetic fluxes emerge to the solar atmosphere. Observations in the EUV passbands of SDO/AIA clearly show the newly formed loops following magnetic reconnection within a vertical current sheet. Formation of the loops is also seen in the H&#945; images taken by NVST. The SDO/HMI observations show that a positive-polarity flux concentration moves toward a negative-polarity one with a speed of ~0.5 km s-1&#160;before the apparent formation of coronal loops. During the formation of coronal loops, we found signatures of flux cancellation and subsequent enhancement of the transverse field between the two polarities. We have reconstructed the three-dimensional magnetic field structure through a magnetohydrostatic model, which shows field lines consistent with the loops in AIA images. Numerous bright blobs with a width of ~1.5 Mm appear intermittently in the current sheet and move upward with apparent velocities of ~80 km s-1. We have also identified plasma blobs moving to the footpoints of the newly formed large loops, with apparent velocities ranging from 30 to 50 km s-1. A differential emission measure analysis shows that the temperature, emission measure and density of the bright blobs are 2.5-3.5 MK, 1.1-2.3&#215;1028&#160;cm-5&#160;and 8.9-12.9&#215;109&#160;cm-3, respectively. Power spectral analysis of these blobs indicates that the magnetic reconnection is inconsistent with the turbulent reconnection scenario.

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Section: Discussionmentioning

confidence: 95%

Formation of solar coronal loops through magnetic reconnection in an emerging active region

Hou¹,

Chen²,

Zhu³

et al. 2021

Preprint

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“…Ion-neutral interactions can lead to increased resistivity and an increase in the effective ion mass, with consequent reduction in the Alfvén speed, steepening of current sheets, heating of the inflow and exhaust regions of reconnection sites, and enhancement of the plasmoid instability (e.g. Zweibel, 1989;Chiueh, 1998;Zweibel et al, 2011;Leake et al, 2012;Mei et al, 2012;Murphy et al, 2012;Zweibel, 2015;Ni et al, 2020). These in turn have important implications for solar phenomena, likely being responsible for increased damping of MHD waves (De Pontieu, Martens, and Hudson, 2001), increased current dissipation and heating of the solar chromosphere (Khomenko and Collados, 2012;Martínez-Sykora, De Pontieu, and Hansteen, 2012), increased flux emergence rates into the corona, reduced Alfvén wave flux from photospheric foot-point motion, and changes in the structure of MHD shocks, prominences, and quiet-Sun magnetic features (see Anan, Ichimoto, and Hillier, 2017, and the references therein).…”

Section: What Is the Three-dimensional Geometry Of The Magnetic Field Near Reconnection Sites? What Roles Do Ion-neutral Collisions Currementioning

confidence: 99%

Critical Science Plan for the Daniel K. Inouye Solar Telescope (DKIST)

Rast¹,

González²,

Rubio³

et al. 2021

Sol Phys

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The National Science Foundation’s Daniel K. Inouye Solar Telescope (DKIST) will revolutionize our ability to measure, understand, and model the basic physical processes that control the structure and dynamics of the Sun and its atmosphere. The first-light DKIST images, released publicly on 29 January 2020, only hint at the extraordinary capabilities that will accompany full commissioning of the five facility instruments. With this Critical Science Plan (CSP) we attempt to anticipate some of what those capabilities will enable, providing a snapshot of some of the scientific pursuits that the DKIST hopes to engage as start-of-operations nears. The work builds on the combined contributions of the DKIST Science Working Group (SWG) and CSP Community members, who generously shared their experiences, plans, knowledge, and dreams. Discussion is primarily focused on those issues to which DKIST will uniquely contribute.

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“…Petschek's model is 'almost uniform' in the sense that the inflow magnetic field is weakly curved, but, since then, it has been generalized to give other fast, almost uniform, reconnection regimes, which depend on the boundary conditions and initial state [8] and have been well established by numerical simulations ( §2a). Indeed, many other details of two-dimensional (2D) reconnection in a range of plasma environments have been studied [9,10].…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional magnetic reconnection in astrophysical plasmas

Priest

Guo

2021

Proc. R. Soc. A.

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Magnetic reconnection is a fundamental process in laboratory, magnetospheric, solar and astrophysical plasmas, whereby magnetic energy is converted into heat, bulk kinetic energy and fast particle energy. Its nature in two dimensions is much better understood than that in three dimensions, where its character is completely different and has many diverse aspects that are currently being explored. Here, we focus on the magnetohydrodynamics of three-dimensional reconnection in the plasma environment of the Solar System, especially solar flares. The theory of reconnection at null points, separators and quasi-separators is described, together with accounts of numerical simulations and observations of these three types of reconnection. The distinction between separator and quasi-separator reconnection is a theoretical one that is unimportant for the observations of energy release. A new paradigm for solar flares, in which three-dimensional reconnection plays a central role, is proposed.

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Magnetic reconnection in partially ionized plasmas

Cited by 37 publications

References 219 publications

Formation of solar coronal loops through magnetic reconnection in an emerging active region

Formation of solar coronal loops through magnetic reconnection in an emerging active region

Critical Science Plan for the Daniel K. Inouye Solar Telescope (DKIST)

Three-dimensional magnetic reconnection in astrophysical plasmas

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Magnetic reconnection in partially ionized plasmas

Cited by 37 publications

References 219 publications

Formation of solar coronal loops through&#160;magnetic reconnection in an emerging active region

Formation of solar coronal loops through&#160;magnetic reconnection in an emerging active region

Critical Science Plan for the Daniel K. Inouye Solar Telescope (DKIST)

Three-dimensional magnetic reconnection in astrophysical plasmas

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Formation of solar coronal loops through magnetic reconnection in an emerging active region

Formation of solar coronal loops through magnetic reconnection in an emerging active region