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arxiv: 2605.16111 · v2 · pith:Q4D326G5new · submitted 2026-05-15 · 🌌 astro-ph.SR

Energy Evolution from the Chromosphere to the Heliosphere in the 2021 October 28 Solar Eruption

Katharine K. Reeves , Daniel B. Seaton , Cynthia Cattell , Bin Chen , Liam David , Federico Fraschetti , Joe Giacalone , Phillip Hess
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Andryi Koval Dana W. Longcope Surajit Mondal Christopher S. Moore Sophie Musset Tatiana Niembro Daniel Pacheco Yeimy J. Rivera Soumya Roy Xudong Sun Durgesh Tripathi Domenico Trotta Matthew J. West Sijie Yu Chunming Zhu
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Pith reviewed 2026-05-20 15:36 UTC · model grok-4.3

classification 🌌 astro-ph.SR
keywords solar eruptioncoronal mass ejectionflare energeticsenergy partitionEUV waveheliospheric propagationmagnetic energy releaseX-class flare
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The pith

The total energy released in the 2021 October 28 solar eruption matches pre-event stored magnetic energy, with CME kinetic and potential energy dominating the partition.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper assembles a complete energy budget for an X1.0 flare and fast coronal mass ejection observed on 28 October 2021. Data from multiple spacecraft near Earth, off the Sun-Earth line, and near the Sun allow tracking of magnetic free energy, non-thermal electrons and ions, radiated bolometric energy, chromospheric deposition, flare-loop thermal energy, EUV-wave dissipation, and the CME's kinetic plus gravitational potential energy in the heliosphere. The authors conclude that the sum of these released energies is consistent with the magnetic energy stored in the active region before the eruption. The CME kinetic and potential terms account for the largest fraction, showing that most energy escapes into the heliosphere rather than being radiated or thermalized near the Sun.

Core claim

We find that the total energy released during the event is consistent with estimates of the pre-event stored magnetic energy, and the CME kinetic + potential energy dominates the energy partition.

What carries the argument

Comprehensive energy budget assembled from remote-sensing, in-situ observations, and scaling laws that converts pre-event magnetic energy into measured components across the chromosphere, corona, and heliosphere.

If this is right

  • The CME carries the majority of released energy outward, implying that heliospheric effects are dominated by the ejected plasma and its shock rather than by flare radiation.
  • Consistency between total output and stored magnetic energy supports using active-region magnetic budgets to forecast overall eruption scale.
  • Flare-related components such as non-thermal electrons, thermal loops, and chromospheric heating together represent a smaller fraction than the CME terms.
  • The global EUV wave accounts for a measurable but secondary share of the energy budget.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The same energy-partition pattern may hold for other fast CMEs from X-class flares, offering a template for modeling space-weather impacts.
  • Future direct measurements of non-thermal ions could test whether the scaling-law estimates used here are generally reliable.
  • Solar-wind and heliospheric models may need to weight CME kinetic input more heavily than flare radiation when simulating energy propagation from the Sun.

Load-bearing premise

Scaling laws based on previous observations accurately estimate quantities such as energy in non-thermal ions, energy deposited in the chromosphere, and energy dissipated by the EUV wave for this specific event.

What would settle it

A direct measurement of non-thermal ion energy or EUV-wave dissipation that differs substantially from the values obtained via scaling laws would break the reported consistency between total released energy and pre-event magnetic energy.

Figures

Figures reproduced from arXiv: 2605.16111 by Andryi Koval, Bin Chen, Christopher S. Moore, Chunming Zhu, Cynthia Cattell, Dana W. Longcope, Daniel B. Seaton, Daniel Pacheco, Domenico Trotta, Durgesh Tripathi, Federico Fraschetti, Joe Giacalone, Katharine K. Reeves, Liam David, Matthew J. West, Phillip Hess, Sijie Yu, Sophie Musset, Soumya Roy, Surajit Mondal, Tatiana Niembro, Xudong Sun, Yeimy J. Rivera.

Figure 1
Figure 1. Figure 1: Locations of BepiColombo, Parker Solar Probe, STEREO-A, Solar Orbiter and Earth (SDO, SoHO, GOES and Wind spacecraft and EOVSA observatory) at the erup￾tion onset time of 2021 October 28 15:00 UT. The event we study is an eruption that occurred on 2021 October 28, originating near the central meridian of the Sun in the southern hemisphere. The eruption produced an X-class flare (SOL2021-10-28T15:17), an EU… view at source ↗
Figure 2
Figure 2. Figure 2 [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: GOES XRS observations of the flare. The peak time is marked with a vertical blue line, and the flare duration is indicated by the blue shading. 2.2. Flare Observations The flare SOL2021-10-28T15:17 was an X1.0 class flare as observed by the X-Ray Sensor (XRS) on GOES, shown in [PITH_FULL_IMAGE:figures/full_fig_p003_3.png] view at source ↗
Figure 3
Figure 3. Figure 3: GOES XRS observations of the flare. The peak time is marked with a vertical blue line, and the flare duration is indicated by the blue shading. This flare was also observed by the Expanded Owens Valley Solar Array (EOVSA), which is a 13 element mi￾crowave interferometer that makes quasi-simultaneous observations over the 1–18 GHz band. The event oc￾curred when the Sun was just rising at EOVSA and only 9 of… view at source ↗
Figure 4
Figure 4. Figure 4: AIA images of the corona in several EUV passbands before the onset of the flare (15:00 UT) and during the flare (15:28 UT). nel et al. 2022) on GOES. AIA provides images in seven EUV passbands (94, 131, 171, 193, 211, 304, and 335 ˚A) as well as several UV channels (1550, 1600, 1700 ˚A) [PITH_FULL_IMAGE:figures/full_fig_p004_4.png] view at source ↗
Figure 4
Figure 4. Figure 4: AIA images of the corona in several EUV passbands before the onset of the flare (15:00 UT) and during the flare (15:28 UT). Frequency (GHZ) Time (October 28,2021) Total power (SFU) Total Power (SFU) GOES 1-8 Å (W/m 2) a) b) c) Helioprojective Latitude (Solar-Y) Helioprojective Longitude (Solar-X) [PITH_FULL_IMAGE:figures/full_fig_p005_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: Panel a): EOVSA dynamic spectrum. The colorbar has been saturated at 1000 SFU. Panel b): The red line shows the smoothed EOVSA lightcurve between 3–15 GHz. The soft X-ray lightcurve obtained from GOES is also shown in the same plot in blue. Panel c): EOVSA image at 13 GHz at 15:28:05 UT, shown with cyan contours over an AIA 1600 ˚A image taken close in time. 15:20 15:25 15:30 15:35 15:40 15:45 15:50 Time (… view at source ↗
Figure 6
Figure 6. Figure 6: STIX soft and hard X-ray contours overplotted on an AIA 1600 ˚A image with an inverted colorscale. STIX light curves from various channels are shown in the bottom panel in comparison to the GOES soft X-ray flux in 1–8 ˚A.. The contours in the top panel are marked with same colors as the light curves in bottom channel. non-thermal energy deposited at the foot-points by the accelerated electrons in Section 3… view at source ↗
Figure 6
Figure 6. Figure 6: STIX soft and hard X-ray contours overplotted on an AIA 1600 ˚A image with an inverted colorscale. STIX light curves from various channels are shown in the bottom panel in comparison to the GOES soft X-ray flux in 1–8 ˚A. The STIX light curves are made with 4 s time bins and the light travel time is taken into account. The contours in the top panel are marked with same colors as the light curves in bottom … view at source ↗
Figure 7
Figure 7. Figure 7: 195 ˚A images of the EUV wave from SUVI and EUVI-A. The upper left image shows a normal view of the wave, enhanced with a radial filter (see Seaton et al. 2023) and temporal unsharp masking technique, while the remaining panels are running difference. The two rightmost panels enclosed in the dashed line show the wave from both GOES and STEREO-A perspectives, separated by about 37.5 ◦ [PITH_FULL_IMAGE:fig… view at source ↗
Figure 7
Figure 7. Figure 7: 195 ˚A images of the EUV wave from SUVI and EUVI-A. The upper left image shows a normal view of the wave, enhanced with a radial filter (see Seaton et al. 2023) and temporal unsharp masking technique, while the remaining panels are running difference. The two rightmost panels enclosed in the dashed line show the wave from both GOES and STEREO-A perspectives, separated by about 37.5 ◦ in longitude and 39 s … view at source ↗
Figure 8
Figure 8. Figure 8: Composite view of the CME using SUVI and C2 data. Arrows indicate the location of the expanding CME as it passes through the LASCO field of view. The CME in the northwest began before the onset of the halo event we study here. Note that the overlaid timestamps correspond to the SUVI image at the center of the frame, which is sampled at higher cadence than the LASCO data [PITH_FULL_IMAGE:figures/full_fig_p… view at source ↗
Figure 8
Figure 8. Figure 8: Composite view of the CME using SUVI and C2 data. Arrows indicate the location of the expanding CME as it passes through the LASCO field of view. The CME in the northwest began before the onset of the halo event we study here. Note that the overlaid timestamps correspond to the SUVI image at the center of the frame, which is sampled at higher cadence than the LASCO data. The animation shows the complete ob… view at source ↗
Figure 9
Figure 9. Figure 9: SolO time-series of flow velocity components in the shock frame (not in the spacecraft frame), magnetic field components in RTN coordinates, and proton density and temperature for the 2021 October 30 shock. The vertical green line in each panel denotes the time of the shock passage and the four vertical lines indicate the start and end times of the upstream and downstream averaging intervals for the IPs an… view at source ↗
Figure 9
Figure 9. Figure 9: SolO time-series of flow velocity components in the shock frame (not in the spacecraft frame), magnetic field components in RTN coordinates, and proton density and temperature for the 2021 October 30 shock. The vertical green line in each panel denotes the time of the shock passage and the four vertical lines indicate the start and end times of the upstream and downstream averaging intervals for the IPs an… view at source ↗
Figure 10
Figure 10. Figure 10: Wind time-series of flow velocity components in the shock frame (not in the spacecraft frame), magnetic field components in RTN coordinates, and proton density and temperature for the 2021 October 31 shock. The verti￾cal green line in each panel denotes the time shock of shock passage and the four vertical lines indicate the upstream and downstream averaging intervals for the IPs analysis in Sec￾tion 3.10… view at source ↗
Figure 11
Figure 11. Figure 11: Top panel: Energy ranges for the SolO/STEP, EPT, and HET instruments used in this study, where solid lines correspond to protons and dashed lines to electrons. The black lines denote the energy ranges that were removed due to overlap.Bottom panel: Energy ranges for the Wind data products used in this study, where solid lines correspond to protons and dashed lines to electrons. The black line over EHSP-e d… view at source ↗
Figure 12
Figure 12. Figure 12: Energy partitioning and flow in the 28 October 2021 event. Underlying CME cartoon modified from Reeves & Forbes (2005). lected times leading to the flare. For each time step, four different models were calculated using different sets of free model parameters following Thalmann et al. (2020). The differences between these four models allow for an estimate of the systematic error. Further, we calculated the… view at source ↗
Figure 14
Figure 14. Figure 14: Magnetic energy flux of AR 12887 based on the PDFI method. Top: instantaneous energy flux. Bottom: ac￾cumulated energy since 2021 October 24 00:00 UT. The val￾ues are from the PDFI database (Hoeksema et al. 2020). Red curves show 2σ formal uncertainty estimate based on a Monte-Carlo method; the uncertainty is small for the accu￾mulated energy. Flux is taken to be zero during HMI data gaps. The vertical do… view at source ↗
Figure 13
Figure 13. Figure 13: Magnetic properties of AR 12887. From top to bottom: Stonyhurst longitude of the AR centroid, unsigned magnetic flux, net electric current, mean torsional parameter α, magnetic energy from extrapolations, and ratio between the magnetic free energy (Ef ) and the potential energy (Ep). Blue, pink, and orange symbols show the results for NLFFF, potential field, and magnetic free energy, respectively. The err… view at source ↗
Figure 15
Figure 15. Figure 15: Comparison between nonthermal energies cal￾culated from STIX data and EOVSA. Yellow shading on the STIX data indicates the error bounds. Note that the EOVSA energies are multiplied by a factor of 10. The cumulative non-thermal energy as a function of time, as inferred from STIX observations is shown in [PITH_FULL_IMAGE:figures/full_fig_p012_15.png] view at source ↗
Figure 15
Figure 15. Figure 15: Comparison between nonthermal energies cal￾culated from STIX data and EOVSA. Yellow shading on the STIX data indicates the error bounds. Note that the EOVSA energies are multiplied by a factor of 10. gyrosynchrotron emission model. The gyrosynchrotron emission spectrum depends on several parameters: the vector magnetic field, the nonthermal electron distribu￾tion, the density and temperature of the therma… view at source ↗
Figure 16
Figure 16. Figure 16: The temporal evolution of the microwave spec￾trum from EOVSA. The flattening of the spectra as time goes on indicates a decreasing number of nonthermal elec￾trons in the flare loop system. from STIX data, likely due to the fact that X-rays and microwaves probe different regions of the flare. While the microwave observations primarily probe nonthermal electrons trapped inside the flaring loop, at the loop … view at source ↗
Figure 16
Figure 16. Figure 16: The temporal evolution of the microwave spec￾trum from EOVSA. The flattening of the spectra as time goes on indicates a decreasing number of nonthermal elec￾trons in the flare loop system. 3.3. Energy in Non-Thermal Ions The best way to measure flare-accelerated ions is us￾ing the 2.223 MeV neutron-capture gamma-ray line, for example as observed by RHESSI (e.g. Shih et al. 2009). Unfortunately this data d… view at source ↗
Figure 18
Figure 18. Figure 18: The chromospheric flare ribbons. (a) is the HMI line-of-sight magnetogram between ±300 G in greyscale. Ribbons from 15:31 UT traced shown as magenta and cyan curves. Regions enclosing most of the ribbons are outlined in red and yellow. (b) A map of all ribbon pixels, showing the time of the peak emission as color, according to a scale shown in a color bar. The ribbon locations from 15:31 UT traced shown a… view at source ↗
Figure 18
Figure 18. Figure 18: The chromospheric flare ribbons. (a) is the HMI line-of-sight magnetogram between ±300 G in greyscale. Ribbons from 15:31 UT traced shown as magenta and cyan curves. Regions enclosing most of the ribbons are outlined in red and yellow. (b) A map of all ribbon pixels, showing the time of the peak emission as color, according to a scale shown in a color bar. The ribbon locations from 15:31 UT traced shown a… view at source ↗
Figure 19
Figure 19. Figure 19: The UFC procedure for inferring power from light curves. (a) shows the ribbon in AIA 1600 ˚A on a logarithmic gray scale. Three pixels are identified by colored diamonds. The light curves from these pixels are plotted in an inset, although without accounting for solar rotation. (b) shows how the light curve of a given ribbon pixel, in this case the cyan pixel from (a), is translated into an energy flux. T… view at source ↗
Figure 19
Figure 19. Figure 19: The UFC procedure for inferring power from light curves. (a) shows the ribbon in AIA 1600 ˚A on a logarithmic gray scale. Three pixels are identified by colored diamonds. The light curves from these pixels are plotted in an inset, although without accounting for solar rotation. (b) shows how the light curve of a given ribbon pixel, in this case the cyan pixel from (a), is translated into an energy flux. T… view at source ↗
Figure 20
Figure 20. Figure 20: Time history of the energy inferred from UFC. (a) shows the accumulated energy of the total (black) and the prompt components (magenta). (b) is the power of the total input (black) prompt component (magenta) and tail compo￾nent (green). (c) shows the rate of magnetic reconnection in the positive (red) and negative (blue) ribbon footpoints [PITH_FULL_IMAGE:figures/full_fig_p017_20.png] view at source ↗
Figure 20
Figure 20. Figure 20: Time history of the energy inferred from UFC. (a) shows the accumulated energy of the total (black) and the prompt components (magenta). (b) is the power of the total input (black) prompt component (magenta) and tail compo￾nent (green). (c) shows the rate of magnetic reconnection in the positive (red) and negative (blue) ribbon footpoints [PITH_FULL_IMAGE:figures/full_fig_p018_20.png] view at source ↗
Figure 21
Figure 21. Figure 21: Global characteristics of the flare from GOES. (a) shows the evolution of the temperature (green) and emis￾sion measure (violet) derived from the two X-ray bands. The bottom axis is in minutes from temperature peak, while the top is UT on 2021 October 28. Evolution under mechanical equilibrium is shown by dashed curves of corresponding col￾ors following the triangle. (b) is a phase portrait formed by plot… view at source ↗
Figure 21
Figure 21. Figure 21: Global characteristics of the flare from GOES. (a) shows the evolution of the temperature (green) and emis￾sion measure (violet) derived from the two X-ray bands. The bottom axis is in minutes from temperature peak, while the top is UT on 2021 October 28. Evolution under mechanical equilibrium is shown by dashed curves of corresponding col￾ors following the triangle. (b) is a phase portrait formed by plot… view at source ↗
Figure 23
Figure 23. Figure 23: Panel (a): The flare arcade in AIA 193 ˚A. Panel (b): the emission measure of the region for 5 < log(T) < 7.4. Panel (c): the DEM weighted temperature of the region. 15:25 15:30 15:35 15:40 15:45 15:50 15:55 16:00 Time (UT) 10 30 erg GOES energy f=1 DEM energy [PITH_FULL_IMAGE:figures/full_fig_p019_23.png] view at source ↗
Figure 23
Figure 23. Figure 23: Panel (a): The flare arcade in AIA 193 ˚A. Panel (b): the emission measure of the region for 5 < log(T) < 7.4. Panel (c): the DEM weighted temperature of the region. 15:25 15:30 15:35 15:40 15:45 15:50 15:55 16:00 Time (UT) 10 30 erg GOES energy f=1 DEM energy [PITH_FULL_IMAGE:figures/full_fig_p020_23.png] view at source ↗
Figure 24
Figure 24. Figure 24: Comparison of thermal energies calculated from GOES flux and from AIA/SUVI DEMs. The shaded black region shows the uncertainties from DEM inversion propa￾gated through the Eq. 10. pears to be the footprint of an essentially spherical 3D wave with many characteristics of a blast wave. This section addresses the wave energy analysis; the kine￾matic evolution of the wave that supports this analysis appears i… view at source ↗
Figure 24
Figure 24. Figure 24: Comparison of thermal energies calculated from GOES flux and from AIA/SUVI DEMs. The shaded black region shows the uncertainties from DEM inversion propa￾gated through the Eq. 10. 3.7. Energy Dissipated by the EUV Wave This event generated a powerful EUV wave that tra￾versed the entirety of the visible solar disk. Multiple authors have examined the energy flux of similar large￾scale waves in the corona (e… view at source ↗
Figure 25
Figure 25. Figure 25: AIA 193 ˚A difference image showing the change in brightness resulting from the wave and the region we used to compute average DEMs (yellow contour). Log T (K) 0 5.0×1028 1.0×1029 1.5×1029 2.0×1029 2.5×1029 DEM per Log T (cm 5 ) 5.6 5.8 6.0 6.2 6.4 6.6 6.8 7.0 [PITH_FULL_IMAGE:figures/full_fig_p020_25.png] view at source ↗
Figure 25
Figure 25. Figure 25: AIA 193 ˚A difference image showing the change in brightness resulting from the wave and the region we used to compute average DEMs (yellow contour). Log T (K) 0 5.0×1028 1.0×1029 1.5×1029 2.0×1029 2.5×1029 DEM per Log T (cm 5 ) 5.6 5.8 6.0 6.2 6.4 6.6 6.8 7.0 [PITH_FULL_IMAGE:figures/full_fig_p021_25.png] view at source ↗
Figure 26
Figure 26. Figure 26: Spatially averaged DEMs before (dashed black line) and during (solid red line) the wave’s passage through the region highlighted in [PITH_FULL_IMAGE:figures/full_fig_p020_26.png] view at source ↗
Figure 26
Figure 26. Figure 26: Spatially averaged DEMs before (dashed black line) and during (solid red line) the wave’s passage through the region highlighted in [PITH_FULL_IMAGE:figures/full_fig_p021_26.png] view at source ↗
Figure 27
Figure 27. Figure 27: Top: Measured CME Mass for the individual images in which the front is visible in COR2 (blue squares). The heights are the outermost edge of the manually deter￾mined region of interest, representing the CME. The dashed line is the fit to the mass evolution equation. The extracted coefficients are provided. The error bars on the height are as￾sumed to be ±10 %. The mass error bars were generated by calcula… view at source ↗
Figure 27
Figure 27. Figure 27: Top: Measured CME Mass for the individual images in which the front is visible in COR2 (blue squares). The heights are the outermost edge of the manually deter￾mined region of interest, representing the CME. The dashed line is the fit to the mass evolution equation. The extracted coefficients are provided. The error bars on the height are assumed to be ±10 %. The mass error bars were generated by calculat… view at source ↗
Figure 28
Figure 28. Figure 28: Properties of the CME at Solar Orbiter, measured at 176.96 R⊙ (left), and Wind, measured at 211.68 R⊙ (right), showing the proton density, speed components in the RTN frame, proton temperature, and magnetic field components and magnitude. The vertical solid and dotted red lines indicate the shock and trailing edge of the CME, respectively. The shaded region prior to and after the shock front are the time … view at source ↗
Figure 28
Figure 28. Figure 28: Properties of the CME at Solar Orbiter, measured at 176.96 R⊙ (left), and Wind, measured at 211.68 R⊙ (right), showing the proton density, speed components in the RTN frame, proton temperature, and magnetic field components and magnitude. The vertical solid and dotted red lines indicate the shock and trailing edge of the CME, respectively. The shaded region prior to and after the shock front are the time … view at source ↗
Figure 29
Figure 29. Figure 29: Energy and Poynting fluxes computed in time for Solar Orbiter (left) and Wind (right). The red vertical lines are the boundary of the CME at both spacecraft discussed in Section 3.9 [PITH_FULL_IMAGE:figures/full_fig_p025_29.png] view at source ↗
Figure 29
Figure 29. Figure 29: Energy and Poynting fluxes computed in time for Solar Orbiter (left) and Wind (right). The red vertical lines are the boundary of the CME at both spacecraft discussed in Section 3.9 [PITH_FULL_IMAGE:figures/full_fig_p026_29.png] view at source ↗
Figure 30
Figure 30. Figure 30: Energy partition for the 2021 October 30 shock at SolO (left) and Wind (right), normalized to unity and ordered based on downstream contribution. The conversion, from upstream to downstream, of the dominant kinetic component into other forms (i.e., thermal and magnetic) with a small fraction available to energize charged particles is apparent. Warmuth & Mann (2020) argued that DEM-based methods tend to ov… view at source ↗
Figure 30
Figure 30. Figure 30: Energy partition for the 2021 October 30 shock at SolO (left) and Wind (right), normalized to unity and ordered based on downstream contribution. The conversion, from upstream to downstream, of the dominant kinetic component into other forms (i.e., thermal and magnetic) with a small fraction available to energize charged particles is apparent. events. On the other hand, Aschwanden et al. (2017) argued tha… view at source ↗
Figure 31
Figure 31. Figure 31: Circular fits to the wave in SUVI (top left) and EUVI-A (top right) observations; color indicates time, with blue earliest and red latest. Bottom panels show the corresponding reconstructed position in latitude and longitude (bottom left; color indicates time as above) and radius and center height above the photosphere (bottom right). respectively, when all quantities are expressed in CGS units. The power… view at source ↗
Figure 31
Figure 31. Figure 31: Circular fits to the wave in SUVI (top left) and EUVI-A (top right) observations; color indicates time, with blue earliest and red latest. Bottom panels show the corresponding reconstructed position in latitude and longitude (bottom left; color indicates time as above) and radius and center height above the photosphere (bottom right). respectively, when all quantities are expressed in CGS units. The power… view at source ↗
Figure 32
Figure 32. Figure 32: Wave radial velocity as a function of distance from the center of the flare site as observed in SUVI’s 195 ˚A passband. Red + symbols indicate points at which the wave is observed on-disk, while blue □ symbols indicate points where the wave is observed above the limb. The dashed line indicates the wave’s final average velocity of ∼ 910 km s−1 , while the shaded band indicates the standard deviation of spe… view at source ↗
Figure 32
Figure 32. Figure 32: Wave radial velocity as a function of distance from the center of the flare site as observed in SUVI’s 195 ˚A passband. Red + symbols indicate points at which the wave is observed on-disk, while blue □ symbols indicate points where the wave is observed above the limb. The dashed line indicates the wave’s final average velocity of ∼ 910 km s−1 , while the shaded band indicates the standard deviation of spe… view at source ↗
read the original abstract

We perform a detailed study of the energetics for a well-observed solar eruption and flare that occurred on 28 October 2021. This event included a GOES class X1.0 flare, a global EUV wave, and a coronal mass ejection that reached speeds of >2000 km/s. The event was observed from a variety of spacecraft in NASA's Heliophysics System Observatory, including multiple missions near Earth, STEREO-A off the Sun-Earth line, and Solar Orbiter, near the Sun-Earth line at about 0.8 au. Using remote sensing, in situ observations, and in some cases scaling laws based on previous observations, we characterize the following quantities: free magnetic energy, energy in non-thermal electrons, energy in non-thermal ions, bolometric energy, energy deposited in the chromosphere, thermal energy radiated in the flare loops, energy dissipated by the EUV wave, CME kinetic and gravitational potential energy, CME energy flux in the heliosphere, and the energy partition in the CME shock. We find that the total energy released during the event is consistent with estimates of the pre-event stored magnetic energy, and the CME kinetic + potential energy dominates the energy partition.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The manuscript presents a multi-spacecraft analysis of the energy budget for the 28 October 2021 X1.0 flare and associated fast CME (>2000 km/s) and global EUV wave. Combining remote-sensing and in-situ data from missions including Solar Orbiter, STEREO-A, and near-Earth observatories, the authors estimate free magnetic energy, non-thermal electron and ion energies, bolometric and chromospheric radiated energies, EUV-wave dissipation, CME kinetic plus gravitational potential energy, and heliospheric energy flux. They conclude that the summed released energy is consistent with the pre-event stored magnetic energy and that CME kinetic plus potential energy dominates the partition.

Significance. If the component estimates hold, the work supplies one of the more complete end-to-end energy inventories for a fast eruption, linking chromospheric deposition to heliospheric transport and reinforcing the observational picture that CME mechanical energy accounts for the majority of the budget. The multi-mission coverage and explicit inclusion of scaling-law terms for otherwise inaccessible quantities are clear strengths.

major comments (2)
  1. [Abstract and energy-estimation sections] Abstract and energy-estimation sections: the headline consistency between total released energy and pre-event magnetic energy, together with the claimed CME dominance, rests on the sum of ~10 terms. Three of these (non-thermal ion energy, chromospheric energy deposition, and EUV-wave dissipation) are obtained exclusively from scaling relations calibrated on earlier, typically slower events. No uncertainty propagation or event-specific cross-check is reported for these three terms; a 30–50 % systematic offset in any one of them would render the numerical agreement and the partition indeterminate.
  2. [Energy estimation sections] The manuscript does not demonstrate that the adopted scaling laws remain valid for a CME speed >2000 km/s and a globally propagating EUV wave; this applicability assumption is load-bearing for the central claim yet is not tested against independent observables available for this event.
minor comments (2)
  1. Notation for the various energy components could be standardized in a single table to improve traceability between the abstract, methods, and results.
  2. Figure captions should explicitly state which energy terms are directly measured versus scaled, and list the source references for each scaling relation.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive and detailed report, which identifies key areas where the energy budget analysis can be strengthened. We address each major comment below and outline revisions to improve the robustness of the presented results.

read point-by-point responses

  1. Referee: [Abstract and energy-estimation sections] Abstract and energy-estimation sections: the headline consistency between total released energy and pre-event magnetic energy, together with the claimed CME dominance, rests on the sum of ~10 terms. Three of these (non-thermal ion energy, chromospheric energy deposition, and EUV-wave dissipation) are obtained exclusively from scaling relations calibrated on earlier, typically slower events. No uncertainty propagation or event-specific cross-check is reported for these three terms; a 30–50 % systematic offset in any one of them would render the numerical agreement and the partition indeterminate.

    Authors: We agree that the three terms derived from scaling relations constitute a significant fraction of the budget and that the absence of explicit uncertainty propagation leaves the numerical agreement vulnerable to systematic offsets. In the revised manuscript we will add a dedicated uncertainty subsection that propagates both statistical and systematic uncertainties for these terms, drawing on the published scatter in the original calibration samples. We will also include a sensitivity analysis that varies each of the three terms by ±30 % and ±50 % while holding the directly measured quantities fixed, thereby quantifying how such offsets would affect the total energy balance and the claimed CME dominance. This addition will make the robustness (or lack thereof) of the headline conclusion transparent to readers. revision: yes

  2. Referee: [Energy estimation sections] The manuscript does not demonstrate that the adopted scaling laws remain valid for a CME speed >2000 km/s and a globally propagating EUV wave; this applicability assumption is load-bearing for the central claim yet is not tested against independent observables available for this event.

    Authors: We acknowledge that the manuscript applies the scaling relations without an explicit test of their validity at the extreme speeds and global scale of this eruption. In revision we will expand the methods and discussion sections to (i) summarize the parameter ranges covered by the original calibration studies and note any fast-CME or global-wave events included in those samples, and (ii) perform limited cross-checks against independent observables already present in the multi-spacecraft dataset—for example, comparing the EUV-wave dissipation estimate with the observed wave amplitude and speed derived from STEREO-A and Solar Orbiter EUV imagery, and comparing the non-thermal ion energy with the in-situ energetic-particle fluence measured near 1 au. Where direct quantitative tests remain limited by the available data, we will explicitly state the extrapolation assumption and its potential impact on the energy partition. These additions will document the degree to which the scaling-law applicability can be supported by this event’s own observations. revision: partial

Circularity Check

0 steps flagged

No significant circularity detected

full rationale

The paper characterizes energies using remote sensing, in situ observations from multiple spacecraft, and scaling laws based on previous observations. No derivation step reduces a claimed prediction or result to a quantity fitted or defined by the paper's own equations. The consistency between total released energy and pre-event magnetic energy is presented as a comparison of independently estimated quantities rather than a self-referential closure. Scaling relations are explicitly attributed to earlier work by other groups, with no load-bearing self-citation chain or ansatz smuggled via prior author work. The central energy partition conclusion therefore rests on external inputs and does not reduce by construction to the study's own fitted values.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The analysis relies on direct spacecraft measurements supplemented by scaling laws derived from earlier solar events; no new theoretical entities or free parameters fitted inside this paper are introduced.

axioms (1)
  • domain assumption Scaling laws based on previous observations can be applied to estimate non-thermal ion energy, chromospheric deposition, and EUV wave dissipation in this event
    Explicitly stated in the abstract as the method used for some quantities when direct measurements were unavailable.

pith-pipeline@v0.9.0 · 5850 in / 1396 out tokens · 64055 ms · 2026-05-20T15:36:25.356197+00:00 · methodology

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