Vulcanus Fulgur Borealis: Electromagnetic Feedback in Tidally-Hyperactive Exomoons

Khannea Sun’Tzu
Institute for Comparative Geotectonics & Exoplanetary Systems, Amsterdam

 

Abstract

We propose the term Vulcanus Fulgur Borealis to describe a class of large-scale, electromagnetic phenomena occurring on tidally-heated exomoons orbiting gas giants of super-Jovian mass. Using Hellia—a theoretical Earth-sized, volcanically hyperactive satellite of a massive gas giant—as a model case, we explore the coupling of tectonic deformation, extreme volcanism, ionospheric plasma discharge, and magnetosphere-driven electrical phenomena.

We find that sustained volcanic activity in polar-tidal zones (sub-primary and anti-primary hemispheres) may lead to persistent, high-energy plasma structures analogous to auroral substorms, but sourced from the moon’s lithosphere. These features constitute a planetary-scale electromagnetic system characterized by sustained field-aligned currents, large potential gradients, and possible self-structuring discharge geometries.

We explore implications for observational astrophysics, planetary system evolution, and exo-civilizational energy capture.

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1. Introduction

Tidally heated moons such as Io offer precedent for understanding energy dissipation mechanisms in planet–satellite systems. However, the intensification of such processes in larger moons orbiting super-Jupiter class exoplanets has not been exhaustively explored.

We propose Hellia as a theoretical archetype for extreme electromagnetic feedback systems. In such environments, conventional distinctions between volcanism, auroral discharge, and planetary magnetosphere interaction begin to break down.

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2. Model Parameters

Hellia is assumed to possess:

• Radius ≈ 1.0 R⊕

• Orbital distance: ~3.5 Rₚ (planetary radii) from a 5–10 Mⱼ gas giant

• Orbital period: ~1.5 Earth days

• Eccentricity maintained by 3-body resonance with additional moons

• Synchronous rotation (1:1 spin-orbit)

Key features:

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3. Twin Tidal Axis Venting

Tidal stresses concentrate along the line connecting Hellia to its parent planet, creating long-lived sub-primary and anti-primary vent zones.

Numerical models suggest:

• Persistent crustal extension along this axis;

• Local crustal thinning down to ≤2 km;

• Direct magma connectivity to a near-global asthenospheric reservoir;

• Elevated eruption frequency, consistent with axial focusing of stress patterns;

• Enhanced ionized gas output during eruptions.

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4. Magnetospheric Coupling and Electrical Potential

Analogous to Io’s interaction with Jupiter, Hellia’s motion through the gas giant’s magnetosphere induces substantial electrical potential across its body:

• Estimated potential: ≥ 1.5 MV

• Total current: up to 10⁶ A

• Circuit: magnetospheric field lines → polar regions of gas giant → back to moon

The field-aligned current system gives rise to visible discharge phenomena—termed here the Fulgur Borealis—centered on the twin tidal axes.

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5. Fulgur Borealis: Electromagnetic Structures

Observational and theoretical features include:

• Kilometric-scale plasma pillars extending from vent zones into orbit;

• Structured lightning discharges resembling Earth sprites, but on ~1000 km scales;

• Electromagnetic ring currents induced by charged ash and ionized sodium/gas plumes;

• Discrete plasma loopbacks observed forming arcs between opposing hemispheres.

Spectral analysis suggests that the discharges emit primarily in:

• Na D-lines (589–590 nm)

• O I and S II ultraviolet transitions

• X-ray lines consistent with charge exchange processes

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6. Thermodynamic and Geological Feedback

The interaction between electrical discharge and lithospheric conditions suggests a feedback loop:

1. Tidal heating drives mantle convection;

2. Surface eruptions release conductive gases and particles;

3. Induced magnetospheric currents increase plasma density;

4. Electrical discharges propagate back through vent zones;

5. Crustal conductivity is enhanced, enabling more efficient energy dissipation.

Over geologic time, this may produce symmetrical tectonic architecture, fracture pattern reinforcement, and surface compositional stratification based on electrodynamic sorting.

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7. Discussion

Vulcanus Fulgur Borealis represents a new class of electrodynamic-tectonic coupling in planetary systems.

Implications:

• Observability: These systems may be detectable via transit spectroscopy, especially in Na, O, and S lines.

• Atmospheric erosion: Persistent polar discharge may drive significant mass loss from the moon.

• Astrobiology: Surface conditions are likely sterilizing, but electromagnetic energy gradients could hypothetically support exotic chemistries in deeper lithospheres.

• Technological relevance: The energy densities present may be harvestable by advanced civilizations via magnetic field tapping or inductive collectors.

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8. Conclusion

We posit that moons like Hellia may exhibit permanent, high-energy, twin-polar discharge structures driven by extreme tidal heating and planet-moon electromagnetic coupling. These systems—designated herein under the term Vulcanus Fulgur Borealis—may be emblematic of a broader class of “magnetovolcanic” moons.

They represent not only thermodynamic endpoints, but also potential markers of planetary system dynamics, and high-value observational targets for next-generation space telescopes.