Height formation of bright points observed by IRIS in Mg II line wings during flux emergence

Grubecka, M.; Schmieder, B.; Berlicki, A.; Heinzel, P.; Dalmasse, K.; Mein, P.

doi:10.1051/0004-6361/201527358

Cited by 50 publications

(72 citation statements)

References 47 publications

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“…Twenty (∼12%) of the identified EBs appear to be associated with UV bursts. This fraction is not that different from the fractions found by Grubecka et al (2016) and Tian et al (2016). Note that a more strict identification of UV bursts relies on an examination of the IRIS spec-tra.…”

Section: Observations and Data Reductionmentioning

confidence: 58%

Flame-like Ellerman Bombs and Their Connection to Solar Ultraviolet Bursts

Chen

Peter

Samanta

et al. 2019

ApJL

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Ellerman bombs (EBs) are small-scale intense brightenings in Hα wing images, which are generally believed to be signatures of magnetic reconnection around the temperature minimum region of the solar atmosphere. They have a flame-like morphology when observed near the solar limb. Recent observations from the Interface Region Imaging Spectrograph (IRIS) reveal another type of small-scale reconnection events, termed UV bursts, in the lower solar atmosphere. Though previous observations have shown a clear coincidence of some UV bursts and EBs, the exact relationship between these two phenomena is still under debate. We investigate the spatial and temporal relationship between flame-like EBs and UV bursts using joint near-limb observations between the 1.6-meter Goode Solar Telescope (GST) and IRIS. In total 161 EBs have been identified from the GST observations, and ∼20 of them reveal signatures of UV bursts in the IRIS images. Interestingly, we find that these UV bursts have a tendency to appear at the upper parts of their associated flame-like EBs. The intensity variations of most EB-related UV bursts and their corresponding EBs match well. Our results suggest that some of these UV bursts and EBs are likely formed at different heights during a common reconnection process.

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Section: Observations and Data Reductionmentioning

confidence: 58%

Flame-like Ellerman Bombs and Their Connection to Solar Ultraviolet Bursts

Chen

Peter

Samanta

et al. 2019

ApJL

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“…Many of the existing works that study this relationship advocate that UV bursts are hot pockets of gas originating very low in the solar atmosphere (even at upper photospheric heights) that would then be heated to transition region temperatures around 8 × 10 4 K (e.g. Peter et al 2014;Vissers et al 2015;Grubecka et al 2016;Tian et al 2016Tian et al , 2018. Using He observations, and being the first to report on EB signatures in the He i D 3 and He i 1083 nm lines, Libbrecht et al (2017) derive EB temperatures of order T ∼ 2 × 10 4 − 10 5 K because they exhibit emission signals in neutral helium triplet lines.…”

Section: Introductionmentioning

confidence: 99%

Ellerman bombs and UV bursts: reconnection at different atmospheric layers

Ortiz

Hansteen

Nóbrega-Siverio

et al. 2020

A&A

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The emergence of magnetic flux through the photosphere and into the outer solar atmosphere produces, amongst other dynamical phenomena, Ellerman bombs (EBs), which are observed in the wings of Hα and are due to magnetic reconnection in the photosphere below the chromospheric canopy. Signs of magnetic reconnection are also observed in other spectral lines, typical of the chromosphere or the transition region. An example are the UV bursts observed in the transition region lines of Si iv and the upper chromospheric lines of Mg ii. In this work we analyze high cadence, high resolution coordinated observations between the Swedish 1-m Solar Telescope (SST) and the Interface Region Imaging Spectrograph (IRIS) spacecraft. Hα images from the SST provide us with the positions, timings and trajectories of EBs in an emerging flux region. Simultaneous, co-aligned IRIS slit-jaw images at 133 (C ii, transition region), 140 (Si iv, transition region) and 279.6 (Mg ii k, core, upper chromosphere) nm, as well as spectroscopy in the far and near ultraviolet from the fast spectrograph raster, allow us to study the possible chromospheric/transition region counterparts of those EBs. Our main goal is to study the possible temporal and spatial relationship between several reconnection events at different layers in the atmosphere (namely EBs and UV bursts), the timing history between them, and the connection of these dynamical phenomena to the ejection of surges in the chromosphere. We also investigate the properties of an extended UV burst and their variations across the burst domain. Our results suggest a scenario where simultaneous and co-spatial EBs and UV bursts are part of the same reconnection system occurring sequentially along a vertical or nearly vertical current sheet. Heating and bidirectional jets trace the location where reconnection takes place. These results support and expand those obtained from recent numerical simulations of magnetic flux emergence.

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“…Improvements in the angular resolution of solar telescopes have allowed many small scale magnetic reconnection events in the low solar atmosphere to be observed (e.g., Yang et al 2015;Xue et al 2016;Zhao et al 2017). The high temperature compact bright points which have UV counterparts that are frequently observed with the Interface Region Imaging Spectrograph (IRIS) (Peter et al 2014;Vissers et al 2015;Grubecka et al 2016;Tian et al 2016) are known as IRIS bombs. They share some characteristics in common with Ellerman Bombs (EBs), e.g., similar life time (about 3-5 min) and size (about 0.3 -0.8 ).…”

Section: Introductionmentioning

confidence: 99%

“…Emission in the Si IV 139.3 nm line requires temperature of at least 2×10 4 K in the dense photosphere or (6−8)×10 4 K from the upper chromosphere to the corona. Some high temperature IRIS bombs might be caused by small flaring arch filaments in the upper chromosphere or the transition regionVissers et al (2015); Grubecka et al (2016). Some of these events identified in Si IV slit-jaws are believed to be generated by magnetic reconnection in the temperature minimum region (TMR) or even in the photosphere (Vissers et al 2015;Grubecka et al 2016;Tian et al 2016).…”

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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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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Height formation of bright points observed by IRIS in Mg II line wings during flux emergence

Cited by 50 publications

References 47 publications

Flame-like Ellerman Bombs and Their Connection to Solar Ultraviolet Bursts

Flame-like Ellerman Bombs and Their Connection to Solar Ultraviolet Bursts

Ellerman bombs and UV bursts: reconnection at different atmospheric layers

Magnetic Reconnection in Strongly Magnetized Regions of the Low Solar Chromosphere

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