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arxiv: 2604.18188 · v1 · submitted 2026-04-20 · 🌌 astro-ph.SR

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Understanding the complex morphology of a CME II: how pre-eruptive conditions shape CME evolution

Abril Sahade , Cecilia Mac Cormack , Angelos Vourlidas , Teresa Nieves-Chinchilla , Cooper Downs , Clementina Sasso , Judith Karpen

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Pith reviewed 2026-05-10 03:59 UTC · model grok-4.3

classification 🌌 astro-ph.SR
keywords magneticpreeruptivecmescoronalfieldmorphologysitubackground
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The pith

The pre-eruptive magnetic configuration of a CME can be robustly determined by matching physics-based simulations to multi-viewpoint observations.

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

The paper tests several possible starting magnetic setups for a complex coronal mass ejection that erupted on 2024 October 26. Using an MHD model, they show that only one combination of magnetic flux rope footpoint locations, force balance, and a near-dated background field reproduces both the large-scale path and the detailed shape seen from three different viewpoints. This match without any fine-tuning suggests the chosen initial conditions reflect the actual pre-eruptive state. The work also compares the simulation to spacecraft measurements of the shock ahead of the CME, showing how interactions with the solar wind affect what is observed in space. Such modeling helps link what we see near the Sun with what arrives at Earth.

Core claim

Using the CORHELCME magnetohydrodynamic model, multiple physically plausible realizations of the pre-eruptive magnetic flux rope and background magnetic field were tested against multiviewpoint remote sensing observations and in situ measurements of the 2024 October 26 CME. Modest changes in MFR footpoint location and force balance produce substantially different coronal trajectories, while only a near-dated background magnetic field yields realistic small-scale morphology. The resulting simulation reproduces key morphologies observed from three viewpoints without fine tuning, indicating that the inferred preeruptive configuration represents a robust, global solution and provides aphysically

What carries the argument

The CORHELCME physics-based magnetohydrodynamic model, which simulates the evolution of candidate pre-eruptive magnetic flux rope configurations and their interaction with the coronal environment to match observed CME morphologies.

Load-bearing premise

Agreement between simulated and observed large-scale propagation and small-scale morphology uniquely constrains the initial MFR footpoint location and force balance.

What would settle it

Finding another pre-eruptive configuration that matches the observed morphologies from three viewpoints and in situ data equally well would falsify the claim of a unique robust solution.

Figures

Figures reproduced from arXiv: 2604.18188 by Abril Sahade, Angelos Vourlidas, Cecilia Mac Cormack, Clementina Sasso, Cooper Downs, Judith Karpen, Teresa Nieves-Chinchilla.

Figure 1
Figure 1. Figure 1: Pre-eruptive configuration and early eruption of the October event. a) HMI magnetogram of AR 13873. The red dashed line marks the PIL. The magenta (orange) dot indicates the northern (southern) footpoint. b) pre-eruption filament observed in AIA 304 at 05:16 UT (white arrow). Footpoints are marked as in panel a). c) First activation at 06:03 UT, with flare ribbon signatures. The southern extension of the r… view at source ↗
Figure 2
Figure 2. Figure 2: Early CME evolution. a) COR1 base-difference images at 06:46 UT. Dashed curves denote features mentioned in the main text (Sec. 2). b) Polarized brightness Metis observations at 07:11 UT processed with the wavelet-optimized whitening (WOW) filter that enhances the edges. c) Similar to panel a) for LASCO C2 at 07:12 UT. d) SoloHI inner FOV (tiles 1 and 2) running-difference images. observations to follow th… view at source ↗
Figure 3
Figure 3. Figure 3: Solar wind data during October 26-31 provided by PSP, SolO, Wind and STA, respectively. From top to bottom we show the total magnetic field [nT], magnetic field component (RTN) [nT], solar wind velocity [km/s] and density [cm−3 ]. Dashed gray vertical lines indicate the CME shock arrival. associated with the interplanetary shock wave arrival. Unfortunately, at PSP and SolO, gaps in the plasma mo￾ments (spe… view at source ↗
Figure 4
Figure 4. Figure 4: Modeling of the MFRs. For each MFR, top left panels show the magnetogram and the segment of the PIL (solid green line) over which the MFR was built. The orange (magenta) dots indicate the positive (negative) footpoint, and the red line connecting them indicates the path of the MFR. The Lorentz force is calculated over the cyan dots and the cyan lines indicate the force direction. Right top panels show, for… view at source ↗
Figure 5
Figure 5. Figure 5: Magnetic field line evolution of MFR4 and its environment. The purple field lines indicate the MFR axis. The open field lines of positive (negative) polarity are shown in red (blue) and the closed overlying field is drawn by the white lines. The north (N) and south pole are indicated in each panel in light blue to depict the orientation. a) the initial state of the simulation (at 06:00 UT). The overlying p… view at source ↗
Figure 6
Figure 6. Figure 6: White-light CME images and modeled field line evolution of MFR4. The top panels show the CME of October event as observed by STA COR1, SolO Metis, LASCO C2,and the tiles 1 and 2 of SoloHI. The middle panels show the field lines of MFR4 in the perspective of STA, SolO, Earth, and SolO again for a later snapshot (from left to right, respectively). For reference, the meridians and FOV of each instrument are p… view at source ↗
Figure 7
Figure 7. Figure 7: a) Slices of the magnetic field components at latitude 6◦ at 34 hours into the MFR1 and MFR4 simulations. The dots indicate the heliospheric position of STA (pink), Wind (teal), SolO (yellow) and PSP (purple). b) Comparison of simulation parameters and observed in-situ data at different heliospheric locations. From left to right: PSP, SolO, Wind, and STA measurements of total magnetic field (top panels), s… view at source ↗
read the original abstract

The morphology and heliospheric impact of coronal mass ejections (CMEs) are strongly shaped by their preeruptive magnetic configuration and surrounding coronal environment, yet these influences remain difficult to constrain observationally. We analyze a complex CME that erupted on 2024 October 26 using multiviewpoint remote sensing observations and in situ measurements. Using the physics based CORHELCME magnetohydrodynamic model, we test multiple physically plausible realizations of the preeruptive magnetic flux rope (MFR) and background magnetic field, using agreement with the observed evolution as a constraint on the CMEs initial state. We find that modest changes in MFR footpoint location and force balance lead to substantially different coronal trajectories, enabling rapid discrimination among candidate initial states. While several configurations reproduce the CMEs large scale propagation, realistic small scale morphology is achieved only when a near dated background magnetic field is employed. The resulting simulation reproduces key morphologies observed from three viewpoints without fine tuning, indicating that the inferred preeruptive configuration represents a robust, global solution and provides a physically consistent interpretation of their magnetic origin. Comparison with in situ shock detections highlights the role of CME solar wind interactions in shaping heliospheric signatures, though shock arrival times remain uncertain at the 11 hr level. These results demonstrate that data informed, physics based modeling can meaningfully constrain CME preeruptive conditions and bridge remote and in situ observations, while emphasizing the need for timely magnetic field measurements to improve predictive capability.

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

3 major / 1 minor

Summary. The paper analyzes a complex CME from 2024 October 26 using multi-viewpoint remote sensing and in-situ data. It employs the CORHELCME MHD model to test multiple pre-eruptive magnetic flux rope (MFR) realizations and background fields, finding that modest variations in MFR footpoint location and force balance produce divergent trajectories. Only one configuration, using a near-dated background field, reproduces both large-scale propagation and realistic small-scale morphology from three viewpoints without fine tuning, which the authors interpret as a robust global solution for the initial state. In-situ shock comparisons highlight solar wind interactions but note 11-hour arrival time uncertainties.

Significance. If validated quantitatively, the work would show that physics-based modeling can constrain CME pre-eruptive conditions from observations, offering a physically consistent link between remote morphology and magnetic origins while highlighting needs for timely magnetograms to improve heliospheric predictions.

major comments (3)
  1. [Abstract] Abstract and results sections: The central claim that the selected MFR configuration reproduces 'key morphologies... without fine tuning' and is a 'robust, global solution' rests on qualitative visual agreement with observed small-scale features; no quantitative metrics (e.g., overlap scores, RMS differences, or feature-specific error bars) are provided to measure agreement or demonstrate that post-hoc selection among tested states was avoided.
  2. [Abstract] Abstract and § on initial state testing: Several configurations are stated to match large-scale propagation, yet discrimination relies entirely on an unspecified notion of 'realistic small-scale morphology' from three viewpoints; without degeneracy tests (e.g., varying model resolution, resistivity, or projection effects) or explicit criteria for what constitutes a match, the uniqueness of the inferred footpoint location and force balance is not established.
  3. [In-situ comparison] In-situ comparison section: The 11-hour uncertainty in shock arrival times is large relative to typical predictive requirements and is presented without specific predicted vs. observed times or sensitivity analysis; this weakens the claim that the simulation bridges remote and in-situ observations in a predictive sense.
minor comments (1)
  1. [Abstract] Abstract: The phrasing 'near dated background magnetic field' is unclear; specify the exact time offset and data source used.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for their thorough and constructive review. We address each major comment below and will make revisions to strengthen the quantitative support and clarity of our claims.

read point-by-point responses
  1. Referee: [Abstract] Abstract and results sections: The central claim that the selected MFR configuration reproduces 'key morphologies... without fine tuning' and is a 'robust, global solution' rests on qualitative visual agreement with observed small-scale features; no quantitative metrics (e.g., overlap scores, RMS differences, or feature-specific error bars) are provided to measure agreement or demonstrate that post-hoc selection among tested states was avoided.

    Authors: We agree that quantitative metrics would improve objectivity. The current version emphasizes visual multi-viewpoint agreement because the tested configurations produced clearly divergent trajectories, with only one matching all observed features simultaneously. In revision we will add overlap scores (Jaccard index) for the CME envelope and RMS differences on key features (leading edge, internal dimple) in the three viewpoints, plus a table ranking all tested states by these metrics to show the selection was not post-hoc. revision: yes

  2. Referee: [Abstract] Abstract and § on initial state testing: Several configurations are stated to match large-scale propagation, yet discrimination relies entirely on an unspecified notion of 'realistic small-scale morphology' from three viewpoints; without degeneracy tests (e.g., varying model resolution, resistivity, or projection effects) or explicit criteria for what constitutes a match, the uniqueness of the inferred footpoint location and force balance is not established.

    Authors: We acknowledge the need for explicit criteria and degeneracy tests. The manuscript already shows that modest footpoint shifts produce visibly different paths, but we will expand the initial-state section with a bulleted list of matching criteria (front alignment, leg visibility, dimple reproduction from each viewpoint) and add new runs varying grid resolution, resistivity, and line-of-sight projection to confirm the solution remains unique within observational uncertainties. revision: yes

  3. Referee: [In-situ comparison] In-situ comparison section: The 11-hour uncertainty in shock arrival times is large relative to typical predictive requirements and is presented without specific predicted vs. observed times or sensitivity analysis; this weakens the claim that the simulation bridges remote and in-situ observations in a predictive sense.

    Authors: The 11-hour spread is indeed large and arises mainly from solar-wind variability between the modeled and actual background. We will revise the section to include a table of exact predicted versus observed shock times at each spacecraft and a short sensitivity study showing how ±10 % changes in solar-wind speed shift the arrival by several hours. This will better frame the remote-to-in-situ connection while transparently noting the current predictive limitation. revision: yes

Circularity Check

0 steps flagged

No significant circularity detected

full rationale

The paper tests discrete candidate initial states for the MFR and background field within the independent CORHELCME MHD model, then selects the configuration whose forward evolution best matches the observed large-scale propagation and small-scale morphology from multiple viewpoints. This is standard constrained inverse modeling rather than a derivation that reduces to its own inputs by construction. No equations or steps are presented as first-principles predictions that turn out to be tautological; the reproduction claim follows directly from running the selected simulation forward, and the robustness argument rests on the fact that only one of the tested plausible states succeeded without post-selection parameter adjustment. The provided text contains no self-citations, ansatzes smuggled via prior work, or renaming of known results that would trigger the enumerated patterns.

Axiom & Free-Parameter Ledger

2 free parameters · 1 axioms · 0 invented entities

The central claim rests on the CORHELCME model's ability to simulate realistic CME evolution from varied initial conditions; limited details available from abstract.

free parameters (2)
  • MFR footpoint location
    Multiple physically plausible locations tested to match observed trajectories
  • MFR force balance parameters
    Modest changes tested as part of initial state variations
axioms (1)
  • domain assumption The CORHELCME magnetohydrodynamic model accurately captures the relevant physics of CME propagation and morphology evolution
    Invoked to use simulation agreement as a constraint on initial states

pith-pipeline@v0.9.0 · 5593 in / 1243 out tokens · 41906 ms · 2026-05-10T03:59:54.445357+00:00 · methodology

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