Stratification of physical parameters in a C-class solar flare using multi-line observations

Abstract

We present high-resolution and multi-line observations of a C2-class solar flare, occurred in NOAA AR 12740 on May 6, 2019. The rise, peak and decay phases of the flare were recorded continuously and quasi-simultaneously in the Ca II K line with the CHROMIS instrument, the Ca II 8542 and Fe I 6173 Ålines with the CRISP instrument at the SST. The observations in the chromospheric Ca II lines exhibit intense brightening near the flare footpoints. At these locations, a non-LTE inversion code was employed to infer the temperature, magnetic field, line-of-sight (LOS) velocity and microturbulent velocity stratification in the flaring atmosphere. During the flare peak time, the LOS velocity shows both upflows and downflows around the flare footpoints in the upper chromosphere and lower chromosphere, respectively. Moreover, the temporal analysis of the LOS magnetic field at the flarepoints exhibits a maximum change of ~600 G. After the flare, the LOS magnetic field decreases to the non-flaring value, exhibiting no permanent or step-wise change. The analysis of response functions to the temperature, LOS magnetic field and velocity shows that the Ca II lines exhibit enhanced sensitivity to the deeper layers (i.e., log_t ~ -3) of the flaring atmosphere, whereas for the non-flaring atmosphere they are mainly sensitive around log_t ~ -4. We suggest that a fraction of the apparent increase in the LOS magnetic field at the flare footpoints may be due to the increase in the sensitivity of the Ca II 8542 Åline in the deeper layers, where the field strength is relatively stronger. The rest can be due to magnetic field reconfiguration during the flare. Our observations illustrate that even a less intense C-class flare can heat the deeper layers of the solar chromosphere, mainly at the flare footpoints, without affecting the photosphere.

arXiv commentShort abstract, 12 figures, 1 table, accepted by A&A

References in corpus (40)

• An Observational Overview of Solar Flares
• CRISP Spectropolarimetric Imaging of Penumbral Fine Structure
• Spectroscopy Made Easy: Evolution
• Solar Flare Prediction Using SDO/HMI Vector Magnetic Field Data with a Machine-Learning Algorithm
• Impulsive phase flare energy transport by large-scale Alfven waves and the electron acceleration problem
• CRISPRED: A data pipeline for the CRISP imaging spectropolarimeter
• An Open Source, Massively Parallel Code for Non-LTE Synthesis and Inversion of Spectral Lines and Zeeman-induced Stokes Profiles
• From coronal observations to MHD simulations, the building blocks for 3D models of solar flares
• STiC -- A multi-atom non-LTE PRD inversion code for full-Stokes solar observations
• The solar chromosphere at high resolution with IBIS. I. New insights from the Ca II 854.2 nm line
• Physical Properties of a Sunspot Chromosphere with Umbral Flashes
• Non-LTE inversions of the Mg II h&k and UV triplet lines
• DELO-Bezier formal solutions of the polarized radiative transfer equation
• Simulations of the Mg II k and Ca II 8542 lines from an Alfvén Wave-heated flare chromosphere
• Abrupt longitudinal magnetic field changes in flaring active regions
• Non-local thermodynamic equilibrium inversions from a 3D MHD chromospheric model
• Radiative diagnostics in the solar photosphere and chromosphere
• SSTRED: Data- and metadata-processing pipeline for CHROMIS and CRISP
• Spectropolarimetric capabilities of Ca II 8542 A line
• Spectral signatures of chromospheric condensation in a major solar flare
• Fast approximation of angle-dependent partial redistribution in moving atmospheres
• First Detection of Chromospheric Magnetic Field Changes During an X1-Flare
• Chromospheric condensations and magnetic field in a C3.6-class flare studied via He I D3 spectro-polarimetry
• How important are electron beams in driving chromospheric evaporation in the 2014 March 29 flare?
• Velocity and Magnetic Transients Driven by the X2.2 White-Light Flare of 2011 February 15 in NOAA 11158
• Three-dimensional modeling of chromospheric spectral lines in a simulated active region
• Spectropolarimetric inversions of the Ca ii 8542 Å line in a M-class solar flare
• On the Origin of a Sunquake during the 29 March 2014 X1 Flare
• Solar image denoising with convolutional neural networks
• A Statistical Study of Photospheric Magnetic Field Changes During 75 Solar Flares
• Temperature constraints from inversions of synthetic solar optical, UV and radio spectra
• Inference of the chromospheric magnetic field configuration of solar plage using the Ca II 8542 Å line
• Hard X-ray footpoint sizes and positions as diagnostics of flare accelerated energetic electrons in the low solar atmosphere
• Magnetic structure of an activated filament in a flaring active region
• Spectropolarimetry of C-class flare footpoints
• Spectroscopic inversions of the Ca ii 8542 Å line in a C-class solar flare
• Non-LTE inversions of a confined X2.2 flare: I. Vector magnetic field in the photosphere and chromosphere
• Physical properties of bright Ca II K fibrils in the solar chromosphere
• Three-dimensional magnetic field structure of a flux emerging region in the solar atmosphere
• Stratification of canopy magnetic fields in a plage region. Constraints from a spatially-regularized weak-field approximation method

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• Bayesian Stokes inversion with Normalizing flows
• The non-LTE formation of the Fe I 6173 A line in the solar atmosphere
• Spectral variations within solar flare ribbons
• Exploring spectropolarimetric inversions using neural fields. Solar chromospheric magnetic field under the weak-field approximation
• A statistical Analysis of Magnetic Field Changes in the Photosphere During Solar Flares Using High-cadence Vector Magnetograms and Their Association with Flare Ribbons
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• Physical properties of a fan-shaped jet backlit by an X9.3 flare
• Chromospheric velocities in an M3.2 flare using He I 1083.0 nm and Ca II 854.2 nm
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• Simultaneous spectropolarimetric observations in the H$\alpha$ and Ca II 8662 Å lines of an active region
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