High Resolution Observations of the Low Atmospheric Response to Small Coronal Heating Events in an Active Region Core
arXiv:2308.15417 · doi:10.3847/1538-4357/acf4f1
Abstract
High resolution spectral observations of the lower solar atmosphere (chromosphere and transition region) during coronal heating events, in combination with predictions from models of impulsively heated loops, provide powerful diagnostics of the properties of the heating in active region cores. Here we analyze the first coordinated observations of such events with the Interface Region Imaging Spectrograph (IRIS) and the CHROMospheric Imaging Spectrometer (CHROMIS), at the Swedish 1-m Solar Telescope (SST), which provided extremely high spatial resolution and revealed chromospheric brightenings with spatial dimensions down to ~150km. We use machine learning methods (k-means clustering) and find significant coherence in the spatial and temporal properties of the chromospheric spectra, suggesting, in turn, coherence in the spatial and temporal distribution of the coronal heating. The comparison of IRIS and CHROMIS spectra with simulations suggest that both non-thermal electrons with low energy (low-energy cutoff ~5keV) and direct heating in the corona transported by thermal conduction contribute to the heating of the low atmosphere. This is consistent with growing evidence that non-thermal electrons are not uncommon in small heating events (nano- to micro-flares), and that their properties can be constrained by chromospheric and transition region spectral observations.
arXiv commentAccepted for publication in the Astrophysical Journal. 21 pages, 13 figures
References in corpus (31)
- The Nuclear Spectroscopic Telescope Array (NuSTAR) Mission
- The Interface Region Imaging Spectrograph (IRIS)
- On Solving the Coronal Heating Problem
- CRISP Spectropolarimetric Imaging of Penumbral Fine Structure
- Does a Non-Magnetic Solar Chromosphere Exist?
- Key Aspects of Coronal Heating
- CRISPRED: A data pipeline for the CRISP imaging spectropolarimeter
- RHESSI Microflare Statistics II. X-ray Imaging, Spectroscopy & Energy Distributions
- Evidence of Non-Thermal Particles in Coronal Loops Heated Impulsively by Nanoflares
- Observing coronal nanoflares in active region moss
- RH 1.5D: a massively parallel code for multi-level radiative transfer with partial frequency redistribution and Zeeman polarisation
- Photometric and Thermal Cross-calibration of Solar EUV Instruments
- Intermittent reconnection and plasmoids in UV bursts in the low solar atmosphere
- SSTRED: Data- and metadata-processing pipeline for CHROMIS and CRISP
- Identifying typical Mg II flare spectra using machine learning
- Microflare Heating of a Solar Active Region Observed with NuSTAR, Hinode/XRT, and SDO/AIA
- What do iris observations of Mg II k tell us about the solar plage chromosphere?
- Investigating the response of loop plasma to nanoflare heating using RADYN simulations
- Accelerated electrons observed down to <7 keV in a NuSTAR solar microflare
- Hinode/Extreme-Ultraviolet Imaging Spectrometer Observations of the Temperature Structure of the Quiet Corona
- IRIS observations of short-term variability in moss associated with transient hot coronal loops
- Active Region Moss: Basic physical parameters and their temporal variation
- Dissecting bombs and bursts: non-LTE inversions of low-atmosphere reconnection in SST and IRIS observations
- Large-amplitude quasi-periodic pulsations as evidence of impulsive heating in hot transient loop systems detected in the EUV with SDO/AIA
- NuSTAR observations of a repeatedly microflaring active region
- Numerical simulations and observations of Mg II in the solar chromosphere
- High-resolution observations of the solar photosphere, chromosphere and transition region. A database of coordinated IRIS and SST observations
- Impulsive coronal heating from large-scale magnetic rearrangements: from IRIS to SDO/AIA
- A Statistical Study of IRIS Observational Signatures of Nanoflares and Non-thermal Particles
- Chromospheric emission from nanoflare heating in RADYN simulations
- Hot plasma in a quiescent solar active region as measured by RHESSI, XRT, and AIA