Heating Mechanisms in the Low Solar Atmosphere Through Magnetic Reconnection in Current Sheets

Ni, Lei; Lin, Jin‐Ming; Roussev, I. I.; Schmieder, B.

doi:10.3847/0004-637x/832/2/195

Cited by 76 publications

(124 citation statements)

References 51 publications

(77 reference statements)

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“…The maximum plasma temperature is above 5 × 10 4 K during the later stage of the reconnection process, which is much higher than that in Case A. These results are consistent with the previous one fluid MHD simulations (Ni et al 2016), where the plasmas were heated from 4200 K to very high temperatures (about 8×10 4 K) with reconnection magnetic fields of 500 G at around the TMR region in that work. However, it is not realistic to have such high temperatures and weakly ionized hydrogen plasmas, which is a reflection of the unphysical nature of the ionization-recombination balance imposed in this calculation.…”

Section: The Non-equilibrium Ionization-recombination Effect In Initisupporting

confidence: 91%

“…Their semi-empirical modeling showed that a higher temperature (higher than 10 4 K) was not compatible with observed Hα and Ca II 8542Å line profiles and that higher temperatures would be inconsistent with observations. Many numerical simulations (e.g., Chen et al 2001;Isobe et al 2007;Archontis & Hood 2009;Xu et al 2011) showed that the maximum temperature increases in magnetic reconnection below the upper chromosphere is always only several thousand K. However, the work by Ni et al (2016) showed that the plasma can be heated from 4200 K to above 8 × 10 4 K during magnetic reconnection in the TMR with strong magnetic field and low plasma β (Ni et al 2016). These simulations included ambipolar diffusion, temperature dependent magnetic diffusion, heat conduction, the optically thin radiative cooling deduced from observations (Gan & Fang 1990) and a heating term, but the plasma was assumed to be in a steady ionization equilibrium state.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic Reconnection in Strongly Magnetized Regions of the Low Solar Chromosphere

Lukin

Murphy

et al. 2018

ApJ

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Magnetic reconnection in strongly magnetized regions around the temperature minimum region of the low solar atmosphere is studied by employing MHD-based simulations of a partially ionized plasma within a reactive 2.5D multi-fluid model. It is shown that in the absence of magnetic nulls in a low β plasma the ionized and neutral fluid flows are well-coupled throughout the reconnection region. However, non-equilibrium ionization-recombination dynamics play a critical role in determining the structure of the reconnection region, lead to much lower temperature increases and a faster magnetic reconnection rate as compared to simulations that assume plasma to be in ionization-recombination equilibrium. The rate of ionization of the neutral component of the plasma is always faster than recombination within the current sheet region even when the initial plasma β is as high as β 0 = 1.46. When the reconnecting magnetic field is in excess of a kilogauss and the plasma β is lower than 0.0145, the initially weakly ionized plasmas can become fully ionized within the reconnection region and the current sheet can be strongly heated to above 2.5 × 10 4 K, even as most of the collisionally dissipated magnetic energy is radiated away. The Hall effect increases the reconnection rate slightly, but in the absence of magnetic nulls it does not result in significant asymmetries or change the characteristics of the reconnection current sheet down to meter scales.

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Section: The Non-equilibrium Ionization-recombination Effect In Initisupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Magnetic Reconnection in Strongly Magnetized Regions of the Low Solar Chromosphere

Lukin

Murphy

et al. 2018

ApJ

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“…Taking the methodology of Innes et al (2015) and Guo et al (2017), we create the synthetic spectral line profiles that might be observed in the reconnection region in the lower atmospheric environments according to the numerical experiment of Ni et al (2016). Ni et al (2016) performed MHD numerical experiments for magnetic reconnection occurring in the temperature minimum region (TMR) and the low chromosphere by including the radiation cooling, the heat conduction, and the ambipolar diffusion. Their results indicated that the plasma could be heated from several 10 3 up to 10 5 K by magnetic reconnection in which the slow-and the fast-mode shocks around the plasmoids formed.…”

Section: Synthetic Spectral Line Profiles Created According To Numerimentioning

confidence: 99%

Multiband Study of a Bidirectional Jet Occurred in the Upper Chromosphere

Cai

Shen

et al. 2019

JGR Space Physics

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We present a study of a jet observed by the Solar Dynamics Observatory (SDO) and the Interface Region Imaging Spectrograph (IRIS), which provide high spatial-temporal resolution observational data of (extreme) ultraviolet images, spectra, and magnetograms. The jet was observed in multiple bands of AIA and manifested clear bidirectional flows in IRIS observations. The emission profiles of the Si IV 1402 Å line of the jet exhibited non-Gaussian features and double-peaked spectra, with the Doppler velocity and the nonthermal velocity up to 100 and 160 km s −1 , respectively. The plasma flows of the jet projected on the sky plane and in the line of sight (LOS) are the typical observational evidence of magnetic reconnection. The EM loci curves indicated that the plasma contains multi-temperature components. The result deduced from the DEM method and changes in intensity of several spectral lines imply that the temperature of the plasma in the jet is heated to at least 10 5.6 K. The electron density is about 10 11 cm −3 according to the intensity ratios of the O IV 1399.77/1401.16 Å doublet and Si IV 1402.77/O IV 1401.16 Å lines. Via different approaches, we reached the conclusion that the jet occurred in the upper chromosphere. Investigating the magnetograms in the period when the jet appeared, we suggest that the jet results from the magnetic reconnection between the moving magnetic structure and the magnetic field nearby.

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“…With the development of the observational technology, more and more features of magnetic reconnection were reported (Savage et al 2010;Liu et al 2010;Zhang et al 2012;Sun et al 2012;Savage et al 2012aSavage et al , 2012bSu et al 2013;Zhang et al 2013;Deng et al 2013;Dudík et al 2014;Tian et al 2014;Yang, Zhang & Xiang 2015;Sun et al 2015;Xue et al 2016;Li et al 2016;Zhu et al 2016;Li et al 2017;Shen et al 2017). Furthermore, many simulations also show evidence that magnetic reconnection plays an important role in solar eruptions (Antiochos et al 1999, Chen & Shibata 2000, Amari et al 2003, Aulanier et al 2010, Janvier et al 2013Ni et al 2016Ni et al , 2017Mei et al 2017;Jiang et al 2016Jiang et al , 2017.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous Observation of a Flux Rope Eruption and Magnetic Reconnection during an X-class Solar Flare

Yan

Yang

Xue

et al. 2018

ApJL

125

103

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In this letter, we present a spectacular eruptive flare (X8.2) associated with a coronal mass ejection (CME) on 2017 September 10 at the west limb of the Sun. A flux rope eruption is followed by the inflow, the formation of a current sheet and a cusp structure, which were simultaneously observed during the occurrence of this flare. The hierarchical layers of the cusp-shaped structure are well observed in 131Å observation. The scenario that can be created from these observations is very consistent with the predictions of some eruptive models. Except for the characteristics mentioned above in the process of the flare predicted by classical eruption models, the current sheet separating into several small current sheets is also observed at the final stage of the flux rope eruption. The quantitative calculation of the velocities and accelerations of the inflow, hot cusp structure, and post-flare loops is presented. The width of the current sheet is estimated to be about 3 × 10 3 km. These observations are very useful to understand the process of solar eruptions.

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Heating Mechanisms in the Low Solar Atmosphere Through Magnetic Reconnection in Current Sheets

Abstract: We simulate several magnetic reconnection processes in the low solar chromosphere/photosphere, the radiation cooling, heat conduction and ambipolar diffusion are all included. Our numerical results indicate that both the high temperature( 8 × 10 4

Cited by 76 publications

References 51 publications

Magnetic Reconnection in Strongly Magnetized Regions of the Low Solar Chromosphere

Magnetic Reconnection in Strongly Magnetized Regions of the Low Solar Chromosphere

Multiband Study of a Bidirectional Jet Occurred in the Upper Chromosphere

Simultaneous Observation of a Flux Rope Eruption and Magnetic Reconnection during an X-class Solar Flare

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