Temperature of Solar Orbiter/EUI quiet Sun small scale brightenings: evidence for a cooler component

Abstract

Context: On 2020 May 30, small and short-lived EUV brightenings were observed in the Quiet Sun (QS) during a four minutes sequence by EUI/HRIEUV on board Solar Orbiter. Their physical origin and possible impact on coronal or Transition Region (TR) heating are still to be determined. Aims: Our aim is to derive the statistical thermal evolution of these events in order to establish their coronal or TR origin. Methods. Our thermal analysis takes advantage of the multithermal sensitivity of the Atmospheric Imaging Assembly (AIA) imager on board the Solar Dynamics Observatory (SDO). We first identified these HRIEUV events in the six coronal bands of AIA. We then performed a statistical time lag analysis, which quantifies the delays between the light curves from different bands. These time lags can give significant insights into the temperature evolution of these events. The analysis is performed taking into account the possible contribution to the results from the background and foreground emissions. Results: The events are characterized by time lags inferior to the AIA cadence of 12 s, for all nine couples of AIA bands analyzed. Our interpretation is the possible co-presence of events which reach or do not reach coronal temperatures ($\approx$ 1MK). We believe that the cool population dominates the events analyzed in this work.

14 pages, 8 figures, language and typo editing, accepted in A&A

References in corpus (21)

• The Solar Orbiter mission -- Science overview
• CHIANTI -- an atomic database for emission lines -- Paper XVI: Version 10, further extensions
• Hot Explosions in the Cool Atmosphere of the Sun
• Highly Efficient Modeling of Dynamic Coronal Loops
• Coronal heating by MHD waves
• A method for the estimation of the significance of cross-correlations in unevenly sampled red-noise time series
• The Unresolved Fine Structure Resolved - IRIS observations of the Solar Transition Region
• The Solar Orbiter Science Activity Plan: translating solar and heliospheric physics questions into action
• Transient small-scale brightenings in the quiet solar corona: a model for campfires observed with Solar Orbiter
• Long-Period Intensity Pulsations in Coronal Loops Explained by Thermal Non-Equilibrium Cycles
• Coronal Fourier power spectra: implications for coronal seismology and coronal heating
• Evidence for Wave Heating of the Quiet Sun Corona
• The magnetic drivers of campfires seen by the Polarimetric and Helioseismic Imager (PHI) on Solar Orbiter
• Extreme-ultraviolet bursts and nanoflares in the quiet-Sun transition region and corona
• Observations of Dissipation of Slow Magneto-acoustic Waves in a Polar Coronal Hole
• Multi-scale observations of thermal non-equilibrium cycles in coronal loops
• Observations of instability-driven nanojets
• On the formation of solar wind & switchbacks, and quiet Sun heating
• Search for photospheric footpoints of quiet Sun transition region loops
• On the Impulsive Heating of Quiet Solar Corona
• Transition region contribution to AIA observations in the context of coronal heating

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• Spectroscopic evidence of cool plasma in quiet Sun HRIEUV small scale brightenings
• Spatial distributions of EUV brightenings in the quiet-Sun
• Small-scale magnetic flux emergence preceding a chain of energetic solar atmospheric events
• Thin coronal jets and plasmoid-mediated reconnection: Insights from Solar Orbiter observations and Bifrost simulations
• Extreme-ultraviolet transient brightenings in the quiet-Sun corona : Closest-perihelion observations with Solar Orbiter/EUI
• Quasi-periodic pulsations in extreme-ultraviolet brightenings
• The nature of small scale EUV solar brightenings investigated as impulsive heating of short loops in 1D hydrododynamics simulations
• Thermodynamic properties of small flares in the quiet Sun observed by H$\alpha$ and EUV: plasma motion of the chromosphere and time evolution of temperature/emission measure
• Investigating explosive events in a 3D quiet-Sun model: Transition region and coronal response
• Accessing the fine temporal scale of EUV brightenings and their quasi-periodic pulsations: 1 second cadence observations by Solar Orbiter/EUI
• Quiet Sun impulsive events observed with NuSTAR during solar minimum
• A multi-viewpoint comparison of the velocity field of coronal propagating disturbances