Multi thermal atmosphere of a mini solar flare during magnetic reconnection observed with IRIS
arXiv:2010.15401 · doi:10.1051/0004-6361/202039229
Abstract
The Interface Region Imaging Spectrograph(IRIS) with its high spatial and temporal resolution brings exceptional plasma diagnostics of solar chromospheric and coronal activity during magnetic reconnection. The aim of this work is to study the fine structure and dynamics of the plasma at a jet base forming a mini flare between two emerging magnetic fluxes (EMFs) observed with IRIS and the Solar Dynamics Observatory (SDO) instruments. We proceed to a spatio-temporal analysis of IRIS spectra observed in the spectral ranges of Mg II, C II, and Si IV ions. Doppler velocities from Mg II lines are computed by using a cloud model technique. Strong asymmetric Mg II and C II line profiles with extended blue wings observed at the reconnection site (jet base) are interpreted by the presence of two chromospheric temperature clouds, one explosive cloud with blueshifts at 290 km/s and one cloud with smaller Dopplershift (around 36 km/s). Simultaneously at the same location (jet base), strong emission of several transition region lines (e.g. O IV and Si IV), emission of the Mg II triplet lines of the Balmer-continuum and absorption of identified chromospheric lines in Si IV broad profiles have been observed and analysed. Such observations of IRIS line and continuum emissions allow us to propose a stratification model for the white-light mini flare atmosphere with multiple layers of different temperatures along the line of sight, in a reconnection current sheet. It is the first time that we could quantify the fast speed (possibly Alfvénic flows) of cool clouds ejected perpendicularly to the jet direction by using the cloud model technique. We conjecture that the ejected clouds come from plasma which was trapped between the two EMFs before reconnection or be caused by chromospheric-temperature (cool) upflow material like in a surge, during reconnection
20 pages, 17 figures, Accepted for publication in Astronomy & Astrophysics
References in corpus (21)
- Hot Explosions in the Cool Atmosphere of the Sun
- Jets in coronal holes: Hinode observations and 3D computer modelling
- RH 1.5D: a massively parallel code for multi-level radiative transfer with partial frequency redistribution and Zeeman polarisation
- On a solar blowout jet: driven mechanism and the formation of cool and hot components
- Ellerman bombs and UV bursts: transient events in chromospheric current sheets
- Hydrogen Balmer Continuum in Solar Flares Detected by the Interface Region Imaging Spectrograph (IRIS)
- Spectral signatures of chromospheric condensation in a major solar flare
- Fine-scale explosive energy release at sites of prospective magnetic flux cancellation in the core of the solar active region observed by Hi-C 2.1, IRIS and SDO
- Compact solar UV burst triggered in a magnetic field with a fan-spine topology
- Density diagnostics derived from the OIV and SIV intercombination lines observed by IRIS
- Explosive events in active region observed by IRIS and SST/CRISP
- Observations and NLTE modeling of Ellerman bombs
- A case-study of multi-temperature coronal jets for emerging flux MHD models
- Dissecting bombs and bursts: non-LTE inversions of low-atmosphere reconnection in SST and IRIS observations
- Observational Evidence of Magnetic Reconnection for Brightenings and Transition Region Arcades in IRIS observations
- Conversion from mutual helicity to self-helicity observed with IRIS
- Investigating the Transition Region Explosive Events and Their Relationship to Network Jets
- IRIS Observations of Spicules and Structures Near the Solar Limb
- Solar Ellerman Bombs in 1-D Radiative Hydrodynamics
- On the origin of the flare emission in IRIS' SJI 2832 filter: Balmer continuum or spectral lines?
- IRIS Mg II Observations and Non-LTE Modeling of Off-limb Spicules in a Solar Polar Coronal Hole
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- Plausibility of ultraviolet burst generation in the low solar chromosphere
- Fan-shaped jet close to a light bridge