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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 2026-05-19 18:47 UTC · model grok-4.3

classification 🌌 astro-ph.SR
keywords solar eruptioncoronal mass ejectionsolar flareenergy partitionEUV waveheliosphereX-class flaremagnetic energy
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The pith

In the 2021 October 28 solar eruption the total released energy matches pre-event stored magnetic energy, with CME kinetic plus 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.

The paper examines the full energy budget of an X1.0 flare accompanied by a global EUV wave and a coronal mass ejection that exceeded 2000 km/s. Using remote-sensing data from multiple spacecraft, in-situ measurements, and scaling relations from earlier events, the authors quantify free magnetic energy, non-thermal particle energies, radiated energy, wave dissipation, and all components of the CME. They report that the summed energy output is consistent with the magnetic energy available before the eruption and that the CME kinetic and gravitational potential energy accounts for the largest share. This accounting matters because it shows how the Sun converts stored magnetic energy into the forms that reach the heliosphere and drive space weather.

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

Multi-spacecraft energy inventory that sums free magnetic energy, non-thermal electron and ion energies, bolometric and chromospheric deposition, EUV-wave dissipation, and CME kinetic, potential, and shock energies.

If this is right

  • The event's energy budget is fully accounted for without requiring additional unseen sources.
  • CME kinetic plus potential energy is the dominant term that propagates into the heliosphere.
  • Energy dissipated by the global EUV wave and deposited in the chromosphere are smaller but measurable fractions.
  • The partition among thermal, non-thermal, and bulk-motion forms can be tracked from chromosphere to 1 au with existing spacecraft.

Where Pith is reading between the lines

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

  • Similar multi-point energy inventories applied to other well-observed eruptions could test whether CME dominance is a general feature of fast events.
  • The consistency between released and stored energy supplies a quantitative benchmark for numerical models that simulate magnetic reconnection and eruption initiation.
  • Knowing the dominant energy carrier (the CME) helps prioritize which observables to monitor for early space-weather alerts.

Load-bearing premise

Scaling laws derived from earlier observations correctly convert remote-sensing and in-situ measurements into energy values for non-thermal particles, EUV wave dissipation, and CME energy flux in this event.

What would settle it

An independent measurement of the pre-eruption free magnetic energy that lies well outside the range of the summed post-eruption energy components would falsify the consistency result.

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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 ↗
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

1 major / 1 minor

Summary. The manuscript performs a multi-spacecraft analysis of the 2021 October 28 X1.0 flare and associated fast CME (>2000 km/s), estimating the energy budget across components including free magnetic energy, non-thermal electrons and ions, bolometric and thermal radiation, chromospheric deposition, EUV wave dissipation, CME kinetic plus gravitational potential energy, heliospheric energy flux, and shock partition. It concludes that the total released energy is consistent with the pre-event stored magnetic energy and that the CME kinetic + potential term dominates the partition.

Significance. A well-observed event with coverage from Solar Orbiter at 0.8 au and other HSO assets allows a rare end-to-end energy accounting from chromosphere to heliosphere; if the quantitative results hold, the work supplies a useful benchmark for eruption energetics models and for testing whether CME kinetic energy systematically dominates in fast events.

major comments (1)
  1. [Abstract] Abstract (methods paragraph): the central consistency claim and the reported dominance of CME kinetic + potential energy rest on scaling laws calibrated on earlier events to convert remote-sensing and in-situ measurements into energies for non-thermal particles, EUV wave dissipation, and CME flux. The manuscript must demonstrate that these scalings remain valid for the specific parameters of this X1.0 event (speed >2000 km/s, multi-spacecraft geometry) or supply propagated uncertainties and sensitivity tests; without such checks the numerical match to pre-event magnetic energy cannot be considered robust.
minor comments (1)
  1. Add explicit citations and functional forms for each scaling relation in the methods section so that readers can reproduce the conversions.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their thorough review and for identifying a key area where the robustness of our energy accounting can be strengthened. We address the concern about scaling-law applicability below and will revise the manuscript accordingly.

read point-by-point responses

  1. Referee: [Abstract] Abstract (methods paragraph): the central consistency claim and the reported dominance of CME kinetic + potential energy rest on scaling laws calibrated on earlier events to convert remote-sensing and in-situ measurements into energies for non-thermal particles, EUV wave dissipation, and CME flux. The manuscript must demonstrate that these scalings remain valid for the specific parameters of this X1.0 event (speed >2000 km/s, multi-spacecraft geometry) or supply propagated uncertainties and sensitivity tests; without such checks the numerical match to pre-event magnetic energy cannot be considered robust.

    Authors: We agree that the applicability of the adopted scaling relations to this fast (>2000 km/s) event requires explicit justification. In the revised manuscript we will add a dedicated subsection (likely in Section 3 or an appendix) that (i) compares the key parameters of the 2021 October 28 event (speed, multi-spacecraft viewing geometry, flare class) with the calibration samples used to derive the scalings for non-thermal particle energy, EUV-wave dissipation, and heliospheric energy flux; (ii) performs sensitivity tests by varying the scaling coefficients within their published 1-sigma uncertainties; and (iii) propagates the resulting range of energies into the final budget, demonstrating that the total released energy remains consistent with the pre-event free magnetic energy within the enlarged error envelope. These additions will make the central consistency claim quantitatively more robust while preserving the original conclusions. revision: yes

Circularity Check

0 steps flagged

No circularity: energy summation uses external scaling laws and independent magnetic energy estimate

full rationale

The paper calculates multiple energy terms from remote-sensing and in-situ data, applying scaling laws drawn from prior observations (external to this work). The central result is a numerical consistency check between the summed released energies and a separately estimated pre-event stored magnetic energy, with CME kinetic+potential terms reported as dominant. No equation or step in the provided text reduces any derived quantity to a fitted parameter or self-citation by construction; the scaling relations are invoked as established external tools rather than derived within the manuscript. This is a standard observational energy-partition study whose validity hinges on the accuracy of those external relations, not on internal self-reference.

Axiom & Free-Parameter Ledger

2 free parameters · 1 axioms · 0 invented entities

Paper invokes scaling laws calibrated on earlier solar events for non-thermal electron/ion energies, EUV wave dissipation, and heliospheric CME flux; these introduce free parameters whose values are taken from prior studies rather than derived here. No new physical entities are postulated. Standard solar-physics assumptions about energy conservation and interpretation of EUV and in-situ signatures are used without re-derivation.

free parameters (2)
  • scaling factors for non-thermal particle energies
    Derived from previous flare observations; applied to convert observed fluxes into energy content for this event.
  • EUV wave energy dissipation efficiency
    Based on prior statistical studies rather than measured directly for this wave.
axioms (1)
  • domain assumption Energy conservation holds across chromosphere, corona, and heliosphere for the tracked components
    Implicit in the summation of all listed energy terms to compare against pre-event magnetic energy.

pith-pipeline@v0.9.0 · 5850 in / 1370 out tokens · 48231 ms · 2026-05-19T18:47:22.253509+00:00 · methodology

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Lean theorems connected to this paper

Citations machine-checked in the Pith Canon. Every link opens the source theorem in the public Lean library.

  • IndisputableMonolith/Cost/FunctionalEquation.lean washburn_uniqueness_aczel unclear
    ?
    unclear

    Relation between the paper passage and the cited Recognition theorem.

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

  • IndisputableMonolith/Foundation/AbsoluteFloorClosure.lean reality_from_one_distinction unclear
    ?
    unclear

    Relation between the paper passage and the cited Recognition theorem.

    scaling laws derived from previous observations accurately convert remote-sensing and in-situ measurements into energy values

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