Eruptive Prominence Ejection

• Eruptive prominence ejection is the rapid expulsion of cool, magnetized plasma from the solar atmosphere, typically triggering flares and coronal mass ejections.
• Observations and models reveal a multi-phase trajectory, including slow-rise, fast-rise, nonradial motion, and significant rotation driven by MHD instabilities and reconnection.
• Energetic signatures such as flare heating, shock excitation, and plasmoid ejection underscore its role in space weather and offer constraints for CME modeling.

Eruptive Prominence Ejection

An eruptive prominence ejection (EPE) is the rapid, large-scale expulsion of magnetized, cool plasma (a prominence or filament) from the solar atmosphere, typically accompanied by a flare and a coronal mass ejection (CME). These events are central to the solar-stellar activity cycle, serve as drivers of space weather, and are key test cases for magnetohydrodynamic (MHD) instability, reconnection, and shock acceleration theory. Modern observations reveal that the prominence is an intrinsic and dynamic component of CME formation, exhibiting a rich sequence of morphological, kinematic, and energetic signatures across all observable regimes (Grechnev et al., 2018, Joshi et al., 2016, Gopalswamy, 2014).

1. Magnetic Structure and Eruption Triggers

Eruptive prominences are generally supported by low-β, current-carrying magnetic flux ropes lying above polarity inversion lines in the solar chromosphere. The pre-eruptive configuration may be a weakly twisted sheared arcade or an already-formed helical flux rope surrounded by an overlying arcade. Prominences show fine-scale, barbed “S” or inverse-“S” structuring, and often exhibit left-handed (dextral, negative-helicity) or right-handed (sinistral, positive-helicity) twist.

Eruption is typically triggered by destabilization mechanisms such as:

• Ideal MHD Instabilities: Helical kink instability (when twist $\Phi \gtrsim 2.5\pi$) or torus instability (when the decay index $$n = -d\ln B_{\text{ext}} / d\ln h > n_{\rm crit}\sim1.5$$) (Chen et al., 2014, Thompson et al., 2011, Koleva et al., 2012).
• Non-Ideal Reconnection: Tether-cutting and breakout reconnection beneath or around the filament “cuts” field-line tethers, reducing the stabilizing tension and allowing the rope to rise (Joshi et al., 2016, Gopalswamy, 2014).
• Mass Unloading: Drainage of plasma along the prominence legs reduces the system’s stabilizing weight, thereby lowering the eruption threshold, with observed redshifting (mass drainage) followed by strong upward blue-shifted ejection (Xue et al., 2021).
• External Disturbances: Coronal jets, flux cancellation, and magnetic flux emergence may prime or destabilize the overlying arcade (Joshi et al., 2016, Devi et al., 2021).

2. Three-Dimensional Structure, Kinematics, and Rotation

Multi-instrument, multi-viewpoint campaigns and analytical/synthetic geometric models (e.g., revised cone and GCS flux rope models) are crucial for reconstructing the dynamic 3D structure and trajectory of erupting prominences (Zhang et al., 2023, Zhang et al., 2024, Zhang et al., 3 May 2025).

Key findings include:

• Launch Phases: Eruptive trajectories generally transition from a slow-rise (few–tens km s$^{-1}$), exponential acceleration (up to several thousand km s$^{-2}$ in extreme cases), to a fast-rise, often saturating at hundreds to thousands km s$^{-1}$ (Zhang et al., 1 Feb 2026, Zhang et al., 2023, Zhang et al., 2024).
• Deflection and Non-Radial Motion: Prominences frequently erupt non-radially, with latitudinal deflections up to $\sim$47$^\circ$ and longitudinal shifts, influenced by large-scale coronal field gradients and active region structures. Early non-radial propagation often dictates the ultimate CME trajectory (Zhang et al., 2023, Zhang et al., 2024, Li et al., 22 Sep 2025).
• Rotation and Writhe: Prominences may undergo large-amplitude ($\gtrsim115^\circ$) axis rotation, especially when kink instability operates, as evidenced both observationally and in 3D MHD modeling (Thompson et al., 2011, Zhang et al., 3 May 2025, Koleva et al., 2012).
• Morphology: Typical configurations include S-shaped, loop–to–cusp transitions, and hollow-cone or shell-like structuring, rather than filled cones, as revealed in Doppler velocity-resolved spectroscopy (Liu et al., 2015).

Table: Representative Kinematic Parameters of Solar Eruptive Prominences

Event / Model	Max Speed ($v_{\rm max}$)	Acceleration ($a_{\rm max}$)	Deflection
SRH+SDO/AIA 16 Mar 2016 (Grechnev et al., 2018)	635 km s$^{-1}$	1.86 km s$^{-2}$	Not quoted
GCS AR 13110 (2022) (Zhang et al., 2023)	708 km s$^{-1}$	1.94 km s$^{-2}$ (mean)	$\sim$15$^\circ$ south
3D Cartwheel CME (2008) (Thompson et al., 2011)	327–380 km s$^{-1}$	38–70 m s$^{-2}$	$>115^\circ$ rotation
31 Dec 2023 X-class (Zhang et al., 1 Feb 2026)	1,476 km s$^{-1}$	2.2 km s$^{-2}$	$35^\circ$ (southeast)
EUV wave-driven (Li et al., 22 Sep 2025)	407 km s$^{-1}$	978 m s$^{-2}$ (early)	$\sim$60$\to$37$^\circ$

3. Energy Release, Heating, and Flare Association

Eruption is powered by the release of stored free magnetic energy:

• Thermal and Non-Thermal Response: Hard X-ray bursts coincide with impulsive acceleration, and EUV/soft X-ray brightenings trace rapid flare heating and reconnection (Grechnev et al., 2018, Joshi et al., 2016, Lee et al., 2017). The heating rate in the rope and overlying loops can peak at $>10^{29}$ erg in the first few minutes after onset, with the emission measure revealing $n_e\sim 10^{10}$ cm$^{-3}$ and $T \sim$ 2–10 MK (Lee et al., 2017).
• Flare–Prominence Timing: Acceleration maxima (eruption “take-off”) are tightly synchronized with nonthermal flare signatures and microwave/HXR bursts, arguing for energetic feedback between upward-driving Lorentz forces and downward reconnection outflows (Grechnev et al., 2018, Joshi et al., 2016).
• Plasmoid Ejection and QPPs: Quasi-periodic pulsations (QPPs) appear in HXR, SXR, and radio during eruptive flares, attributed to plasmoid-mediated reconnection in the vertical current sheet below the erupting rope (Li et al., 22 Sep 2025).
• Shock Waves: Fast prominence ejection impulsively excites blast-wave–like MHD shocks, evidenced by global EUV waves and type II radio bursts. These typically develop at heights $h\sim 0.1$–0.75 $R_\odot$ above the photosphere, with coronal Mach numbers $M_s\approx4$–7 (Grechnev et al., 2018, Zhang et al., 1 Feb 2026).

4. Relationship with Coronal Mass Ejections and Their Structure

Eruptive prominences are structurally and dynamically integral to CME formation (Gopalswamy, 2014, Yashiro et al., 2020, Chen et al., 2014):

• Three-Part CME Morphology: The cool, dense prominence plasma forms the core of the classical three-part CME (bright LE, dark cavity, bright core), generally propagating a factor 1.2–2.3 more slowly than the CME front, reflecting differential acceleration by the expanding magnetic flux rope (Zhang et al., 2023, Zhang et al., 2024, Mierla et al., 2022).
• Coupling and Detachment: Prominence material may eventually detach from the CME shell, with differential deceleration or coasting in the heliosphere, as established by in situ, coronagraphic, and heliospheric imager tracking to 1 AU (Wood et al., 2015).
• Deflection Modeling: Generic and event-specific models consistently find that nonradial eruption—controlled by coronal field distributions—imprints on the propagation direction of both the core and CME shell (Zhang et al., 2023, Zhang et al., 3 May 2025, Zhang et al., 2024).

5. Observational Diagnostics and Statistical Properties

Rigorous detection, reconstruction, and plasma diagnostics integrate multiwavelength, multipoint approaches:

• Imaging and Kinematics: EUV imagers (SDO/AIA, Solar Orbiter/EUI/FSI, STEREO/EUVI) deliver high-cadence, multi-angle coverage, while coronagraphs (SOHO/LASCO, STEREO/COR) enable continuous tracking from the low corona to >10 $R_\odot$ (Wood et al., 2015, Mierla et al., 2022, Zhang et al., 2024). Automated catalogs leverage thresholding and connected-component extraction to compile large-scale statistics—angular widths $\sim$7°, centroid speed decay constants $\sim$40 km s$^{-1}$—with clear correlations to the solar cycle and polar field strength (Yashiro et al., 2020).
• Spectroscopic and Plasma Diagnostics: IRIS, ground-based Hα, and multi-EUV spectroscopy yield Doppler shifts, density, and line-ratio diagnostics for both ascent (upflows), fallback (downflows), mass-drainage episodes, and kinematic substructure (Xue et al., 2021, Liu et al., 2015, Hong-Peng et al., 2024).
• Electron Acceleration Tracers: Radio spectrographs observe herringbone and type II fine structures, directly quantifying shock-accelerated beam speeds (0.04–0.41$c$) and establishing the prominence-shock interface height (Zhang et al., 1 Feb 2026).

6. Physical Implications and Modeling Constraints

Cohesive modeling of eruptive prominence ejection now incorporates:

• Flux Rope Universality: A twisted flux-rope channel (with supporting evidence for ongoing formation or pre-existence via barbs, cavities, hot envelopes, and cool cores) is required for CME initiation (Chen et al., 2014, Gopalswamy, 2014, Koleva et al., 2012).
• Combined Ideal and Non-Ideal Physics: Instabilities (kink, torus), reconnection (tether-cutting, breakout), and nonlinear feedback between plasmoid ejection and bulk rope acceleration collectively act in launch and acceleration (Joshi et al., 2016, Grechnev et al., 2018, Lee et al., 2017, Li et al., 22 Sep 2025).
• Deflection and Space-Weather Impact: Early nonradial motion set by ambient fields (not post-launch drag), as well as shock excitation and SEP acceleration closely tied to the impulsive prominence phase, are essential to forecasting Earth- and exoplanet-impacting events (Grechnev et al., 2018, Gopalswamy, 2014, Zhang et al., 2023, Zhang et al., 2024).
• Energetic Connectivity: CME kinetic energy ($10^{30-32}$ erg) is sourced directly from eruptive current-carrying field regions in the flux rope volume $V$, as $E_{\rm kin}\sim \frac12 M V^2$ matches the locally liberated $E_{\rm mag} = \int_V B^2/(2\mu_0)\,dV$ (Gopalswamy, 2014, Lee et al., 2017).

7. Extensions: Stellar Prominence Ejection

The solar paradigm extends to stellar analogs, with spectroscopic detection of extreme Hα blue-wing enhancements ($v_{\rm max}\sim -600$ km s$^{-1}$) and inferred CME-prominence masses $M_{\rm CME}$ up to $10^{19}$ g and relative mass ratios $\sim 10^{-14}$, confirming that MHD-instability-driven, mass-laden prominence ejections are ubiquitous and robust sources of mass and angular momentum loss for active M dwarfs (Hong-Peng et al., 2024).

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References (all technical details, equations, and events as cited above are strictly documented in articles: (Grechnev et al., 2018, Joshi et al., 2016, Gopalswamy, 2014, Xue et al., 2021, Devi et al., 2021, Zhang et al., 2023, Liu et al., 2015, Zhang et al., 1 Feb 2026, Chen et al., 2014, Lee et al., 2017, Koleva et al., 2012, Yashiro et al., 2020, Zhang et al., 2024, Wood et al., 2015, Thompson et al., 2011, Hong-Peng et al., 2024, Li et al., 22 Sep 2025, Zhang et al., 3 May 2025, Mierla et al., 2022)).