Magnetic reconnection at the earliest stage of solar flux emergence
arXiv:1801.06785 · doi:10.3847/1538-4357/aaaae6
Abstract
On 2016 September 20, the Interface Region Imaging Spectrograph observed an active region during its earliest emerging phase for almost 7 hours. The Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory observed continuous emergence of small-scale magnetic bipoles with a rate of 10 Mx~s. The emergence of magnetic fluxes and interactions between different polarities lead to frequent occurrence of ultraviolet (UV) bursts, which exhibit as intense transient brightenings in the 1400 Å images. In the meantime, discrete small patches with the same magnetic polarity tend to move together and merge, leading to enhancement of the magnetic fields and thus formation of pores (small sunspots) at some locations. The spectra of these UV bursts are characterized by the superposition of several chromospheric absorption lines on the greatly broadened profiles of some emission lines formed at typical transition region temperatures, suggesting heating of the local materials to a few tens of thousands of kelvin in the lower atmosphere by magnetic reconnection. Some bursts reveal blue and red shifts of 100~km~s at neighboring pixels, indicating the spatially resolved bidirectional reconnection outflows. Many such bursts appear to be associated with the cancellation of magnetic fluxes with a rate of the order of 10 Mx~s. We also investigate the three-dimensional magnetic field topology through a magneto-hydrostatic model and find that a small fraction of the bursts are associated with bald patches (magnetic dips). Finally, we find that almost all bursts are located in regions of large squashing factor at the height of 1 Mm, reinforcing our conclusion that these bursts are produced through reconnection in the lower atmosphere.
ApJ, 10 figures
References in corpus (31)
- The Solar Optical Telescope for the Hinode Mission: An Overview
- Chromospheric Anemone Jets as Evidence of Ubiquitous Reconnection
- Small-scale filament eruptions as the driver of solar coronal hole X-ray jets
- Hot Explosions in the Cool Atmosphere of the Sun
- Prevalence of Small-scale Jets from the Networks of the Solar Transition Region and Chromosphere
- Imaging and spectroscopic observations of magnetic reconnection and chromospheric evaporation in a solar flare
- Bombs and flares at the surface and lower atmosphere of the Sun
- Frequently Occurring Reconnection Jets from Sunspot Light Bridges
- Intermittent reconnection and plasmoids in UV bursts in the low solar atmosphere
- Magnetic reconnection between small-scale loops observed with the New Vacuum Solar Telescope
- Heating mechanisms in the low solar atmosphere through magnetic reconnection in current sheets
- Blob formation and ejection in coronal jets due to the plasmoid and Kelvin-Helmholtz instabilities
- Extreme Ultraviolet Imaging of Three-dimensional Magnetic Reconnection in a Solar Eruption
- Spectral observations of Ellerman bombs and fitting with a two-cloud model
- Simulating Ellerman bomb-like event
- Small-Scale Structuring Of Ellerman Bombs at Solar Limb
- Compact solar UV burst triggered in a magnetic field with a fan-spine topology
- Explosive events on sub-arcsecond scale in IRIS observations: a case study
- Magnetic reconnection in strongly magnetized regions of the low solar chromosphere
- IRIS Burst Spectra Co-Spatial To A Quiet-Sun Ellerman-Like Brightening
- Various Local Heating Events in the Earliest Phase of Flux Emergence
- Observations and NLTE modeling of Ellerman bombs
- Observational Evidence of Magnetic Reconnection for Brightenings and Transition Region Arcades in IRIS observations
- Asymmetric Magnetic Reconnection in Weakly Ionized Chromospheric Plasmas
- Investigating Energetic X-Shaped Flares on the Outskirts of A Solar Active Region
- Observations of Ellerman bomb emission features in He I D3 and He I 10830 Å
- On The Relationship Between Magnetic Cancellation and UV Burst Formation
- Multi-wavelength Spectral Analysis of Ellerman Bombs Observed by FISS and IRIS
- Solar Ellerman Bombs in 1-D Radiative Hydrodynamics
- RADYN simulations of non-thermal and thermal models of Ellerman bombs
- Can the temperature of Ellerman Bombs be more than 10000K?
Cited by in corpus (41)
- Solar ultraviolet bursts
- A Cancellation Nanoflare Model for Solar Chromospheric and Coronal Heating
- Transient small-scale brightenings in the quiet solar corona: a model for campfires observed with Solar Orbiter
- Probing the physics of the solar atmosphere with the Multi-slit Solar Explorer (MUSE): I. Coronal Heating
- Plasmoid-mediated reconnection in solar UV bursts
- Ellerman bombs and UV bursts: reconnection at different atmospheric layers
- Flame-like Ellerman Bombs and Their Connection to Solar UV Bursts
- Onset of secondary instabilities and plasma heating during magnetic reconnection in strongly magnetized regions of the low solar atmosphere
- A Magnetic Reconnection model for Hot Explosions in the Cool Atmosphere of the Sun
- IRIS observations of magnetic interactions in the solar atmosphere between pre-existing and emerging magnetic fields. II. UV emission properties
- A Cancellation Nanoflare Model for Solar Chromospheric and Coronal Heating III. 3D Simulations and Atmospheric Response
- The Birth of a Jet-driven Twin CME and Its Deflection from Remote Magnetic Fields
- A White-light Flare Powered by Magnetic Reconnection in the Lower Solar Atmosphere
- Spectroscopic and imaging observations of small-scale reconnection events
- Magnetic reconnection in the low solar chromosphere with a more realistic radiative cooling model
- Multi thermal atmosphere of a mini solar flare during magnetic reconnection observed with IRIS
- Solar Ultraviolet Bursts in a Coordinated Observation of IRIS, Hinode and SDO
- Magnetic loops above a small flux-emerging region observed by IRIS, Hinode and SDO
- ALMA observations of transient heating in a solar active region
- Formation of solar quiescent coronal loops through magnetic reconnection in an emerging active region
- Observations of solar chromospheric heating at sub-arcsec spatial resolution
- Three-dimensional magnetic field structure of a flux emerging region in the solar atmosphere
- Macrospicules and Their Connection to Magnetic Reconnection in the Lower Atmosphere
- Transition-region explosive events produced by plasmoid instability
- High flow speeds and transition-region like temperatures in the solar chromosphere during flux emergence
- Transition region loops in the very late phase of flux-emergence in IRIS sit-and-stare observations
- Toward a fast and consistent approach to model solar magnetic fields in multiple layers
- The Ellerman bomb and Ultraviolet burst triggered successively by an emerging magnetic flux rope
- Magnetic Topology of quiet-Sun Ellerman bombs and associated Ultraviolet brightenings
- Naked emergence of an anti-Hale active region I. Overall evolution and magnetic properties
- Spectroscopic and Imaging Observations of Spatially Extended Magnetic Reconnection in the Splitting of a Solar Filament Structure
- Small-scale dynamic phenomena associated with interacting fan-spine topologies: quiet-Sun Ellerman bombs, UV brightenings, and chromospheric inverted-Y-shaped jets
- A New Approach to Solar Flare Prediction
- Small-scale Bright Blobs Ejected from a Sunspot Light Bridge
- Data-constrained 3D MHD Simulation of a Spiral Jet Caused by an Unstable Flux Rope Embedded in Fan-spine Configuration
- A new view of the solar interface region from the Interface Region Imaging Spectrograph (IRIS)
- Signatures of Untwisting Magnetic Field in a Small Emerging Bipole in the Solar Photosphere
- Data-driven Radiative Magnetohydrodynamics Simulations with the MURaM Code: Coronal Heating and Dynamics in an Emerging Active Region
- SolO/EUI Observations of Ubiquitous Fine-scale Bright Dots in an Emerging Flux Region: Comparison with a Bifrost MHD Simulation
- Parallel plasma loops and the energization of the solar corona
- Nature of the energy source powering solar coronal loops driven by nanoflares