scholarly journals Observational Evidence of Magnetic Reconnection in the Terrestrial Bow Shock Transition Region

2019 ◽  
Vol 46 (2) ◽  
pp. 562-570 ◽  
Author(s):  
Shan Wang ◽  
Li‐Jen Chen ◽  
Naoki Bessho ◽  
Michael Hesse ◽  
Lynn B. Wilson ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
Transition Region ◽  
Observational Evidence ◽  
Bow Shock ◽  
Shock Transition

scholarly journals Observational Evidence of Magnetic Reconnection for Brightenings and Transition Region Arcades inIRISObservations

2017 ◽  
Vol 836 (1) ◽  
pp. 52 ◽  
Author(s):  
Jie Zhao ◽  
Brigitte Schmieder ◽  
Hui Li ◽  
Etienne Pariat ◽  
Xiaoshuai Zhu ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
Transition Region ◽  
Observational Evidence

scholarly journals The Location of Magnetic Reconnection at Earth’s Magnetopause

2021 ◽  
Vol 217 (3) ◽  
Author(s):  
K. J. Trattner ◽  
S. M. Petrinec ◽  
S. A. Fuselier
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Reconnection ◽  
Ion Beams ◽  
Review Article ◽  
Observational Evidence ◽  
Magnetic Shear ◽  
General Direction ◽  
Shear Model ◽  
Wide Range

AbstractOne of the major questions about magnetic reconnection is how specific solar wind and interplanetary magnetic field conditions influence where reconnection occurs at the Earth’s magnetopause. There are two reconnection scenarios discussed in the literature: a) anti-parallel reconnection and b) component reconnection. Early spacecraft observations were limited to the detection of accelerated ion beams in the magnetopause boundary layer to determine the general direction of the reconnection X-line location with respect to the spacecraft. An improved view of the reconnection location at the magnetopause evolved from ionospheric emissions observed by polar-orbiting imagers. These observations and the observations of accelerated ion beams revealed that both scenarios occur at the magnetopause. Improved methodology using the time-of-flight effect of precipitating ions in the cusp regions and the cutoff velocity of the precipitating and mirroring ion populations was used to pinpoint magnetopause reconnection locations for a wide range of solar wind conditions. The results from these methodologies have been used to construct an empirical reconnection X-line model known as the Maximum Magnetic Shear model. Since this model’s inception, several tests have confirmed its validity and have resulted in modifications to the model for certain solar wind conditions. This review article summarizes the observational evidence for the location of magnetic reconnection at the Earth’s magnetopause, emphasizing the properties and efficacy of the Maximum Magnetic Shear Model.

scholarly journals Statistics of Reconnecting Current Sheets in the Transition Region of Earth's Bow Shock

2020 ◽  
Vol 125 (1) ◽  
Author(s):  
I. Gingell ◽  
S. J. Schwartz ◽  
J. P. Eastwood ◽  
J. E. Stawarz ◽  
J. L. Burch ◽  
...  
Keyword(s):  
Transition Region ◽  
Bow Shock ◽  
Current Sheets ◽  
Earth’S Bow Shock

scholarly journals Why are CMEs large-scale coronal events: nature or nurture?

2008 ◽  
Vol 26 (10) ◽  
pp. 3077-3088 ◽  
Author(s):  
L. van Driel-Gesztelyi ◽  
G. D. R. Attrill ◽  
P. Démoulin ◽  
C. H. Mandrini ◽  
L. K. Harra
Keyword(s):  
Magnetic Reconnection ◽  
Large Scale ◽  
Observational Evidence ◽  
Angular Width ◽  
Small Scale ◽  
Apparent Contradiction ◽  
Lower Corona ◽  
Magnetic Structures ◽  
Source Regions ◽  
Scale Response

Abstract. The apparent contradiction between small-scale source regions of, and large-scale coronal response to, coronal mass ejections (CMEs) has been a long-standing puzzle. For some, CMEs are considered to be inherently large-scale events – eruptions in which a number of flux systems participate in an unspecified manner, while others consider magnetic reconnection in special global topologies to be responsible for the large-scale response of the lower corona to CME events. Some of these ideas may indeed be correct in specific cases. However, what is the key element which makes CMEs large-scale? Observations show that the extent of the coronal disturbance matches the angular width of the CME – an important clue, which does not feature strongly in any of the above suggestions. We review observational evidence for the large-scale nature of CME source regions and find them lacking. Then we compare different ideas regarding how CMEs evolve to become large-scale. The large-scale magnetic topology plays an important role in this process. There is amounting evidence, however, that the key process is magnetic reconnection between the CME and other magnetic structures. We outline a CME evolution model, which is able to account for all the key observational signatures of large-scale CMEs and presents a clear picture how large portions of the Sun become constituents of the CME. In this model reconnection is driven by the expansion of the CME core resulting from an over-pressure relative to the pressure in the CME's surroundings. This implies that the extent of the lower coronal signatures match the final angular width of the CME.

scholarly journals Solar activities observed with the New Vacuum Solar Telescope

2015 ◽  
Vol 11 (S320) ◽  
pp. 315-320
Author(s):  
Shuhong Yang ◽  
Jun Zhang
Keyword(s):  
Magnetic Reconnection ◽  
Flux Rope ◽  
Observational Evidence ◽  
Small Scale ◽  
Solar Telescope ◽  
New Name ◽  
Direct Observations ◽  
Filament Activation ◽  
First Time

AbstractBased on the New Vacuum Solar Telescope observations, some new results about the solar activities are obtained. (1) In the Hα line, a flux rope tracked by filament activation is detected for the first time. There may exist some mild heating during the filament activation. (2) The direct observations illustrate the mechanism of confined flares, i.e., the flares are triggered by magnetic reconnection between the emerging loops and the pre-existing loops and prevented from being eruptive by the overlying loops. (3) The solid observational evidence of magnetic reconnection between two sets of small-scale loops is reported. The successive slow reconnection changes the conditions around the reconnection area and leads to the rapid reconnection. (4) An ensemble of oscillating bright features rooted in a light bridge is observed and given a new name, light wall. The light wall oscillations may be due to the leakage of p-modes from below the photosphere.

Mid‐Latitude Spread‐F Structures Over the Geomagnetic Low‐Mid Latitude Transition Region: An Observational Evidence

2020 ◽  
Vol 125 (5) ◽  
Author(s):  
M. Sivakandan ◽  
S. Mondal ◽  
S. Sarkhel ◽  
D. Chakrabarty ◽  
M. V. Sunil Krishna ◽  
...  
Keyword(s):  
Transition Region ◽  
Observational Evidence ◽  
Spread F

The dynamics of electron–ion coupling in the shock transition region

2003 ◽  
Vol 10 (4) ◽  
pp. 1113-1119 ◽  
Author(s):  
Nobue Shimada ◽  
Masahiro Hoshino
Keyword(s):  
Transition Region ◽  
Shock Transition

scholarly journals Ellerman bombs and UV bursts: reconnection at different atmospheric layers

2020 ◽  
Vol 633 ◽  
pp. A58 ◽  
Author(s):  
Ada Ortiz ◽  
Viggo H. Hansteen ◽  
Daniel Nóbrega-Siverio ◽  
Luc Rouppe van der Voort
Keyword(s):  
Magnetic Flux ◽  
Magnetic Reconnection ◽  
Transition Region ◽  
Spatial Relationship ◽  
Spectral Lines ◽  
Near Ultraviolet ◽  
Temporal And Spatial ◽  
Imaging Spectrograph ◽  
High Cadence ◽  
Ellerman Bombs

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 ultraviolet (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 1m 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 and 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.

scholarly journals Magnetic reconnection and kinetic waves generated in the Earth's quasi-parallel bow shock

2020 ◽  
Vol 27 (9) ◽  
pp. 092901
Author(s):  
N. Bessho ◽  
L.-J. Chen ◽  
S. Wang ◽  
M. Hesse ◽  
L. B. Wilson ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
Bow Shock
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