Starivore Energy Budget

Clément Vidal's stellivore hypothesis: spider pulsars as possible civilisations feeding on a companion star — spin-down power, interception fraction, and Kardashev position

🔬 Established physics (spin-down, binary geometry) ⚠ Theoretical (stellivore interpretation) ✦ Engineering fiction (Kardashev application)
Context. In Stellivore Extraterrestrials? Binary Stars as Living Systems (Vidal 2016), Clément Vidal proposes that advanced civilisations could feed on the radiation output of a companion star via a binary pulsar arrangement. Spider pulsars — millisecond pulsars whose wind is actively ablating a low-mass companion — are the observational candidates. This tool applies Vidal's energy budget formalism to any pulsar binary and asks: is the intercepted luminosity anomalous relative to natural stellar evolution?
Pulsar Parameters
Period, spin-down rate, and moment of inertia determine the rotational energy reservoir and luminosity
Spin period P (ms) 1.607
0.63 ms10 ms100 ms
Period derivative Ṗ (s/s) 1.68×10⁻²⁰
10⁻²²10⁻¹⁹10⁻¹⁶
Binary Geometry
Orbital separation and companion size set the interception fraction of the pulsar wind
Orbital separation a (R☉) 2.49
0.5 R☉31050
Companion radius R_c (R☉) 0.14
0.01 R☉0.11.03.0
Companion mass M_c (M☉) 0.025
0.01 M☉0.11.03.0
Geometric interception fraction f
0.000796
R_c² / (4a²) — fraction of pulsar wind intercepted by companion
Energy Budget
Rotational energy reservoir, spin-down luminosity, and intercepted flux
Spin-down luminosity L_sd
1.60×10²⁸
W  ·  4.18×10¹ L☉
Intercepted luminosity L_int
1.27×10²⁵
W  ·  3.32×10⁻² L☉
Surface B-field B_s
3.31×10⁸
G (gauss)
Characteristic age τ_c
1.52×10⁹
yr (= P / 2Ṗ)
Eddington limit L_Edd
3.15×10²⁹
W (for companion mass)
Companion ablation time
1.78×10¹⁶
yr (M_c c² / L_int)
L_int / L_companion_natural = — (ratio >1 means irradiation dominates)
Kardashev position — spin-down luminosity L_sd (watts, log scale)
Type I (10¹⁶)
Type II (4×10²⁶)
Type III (4×10³⁷)
K-level (L_sd) K = 1.76
Intercepted luminosity L_int
K-level (L_int) K = 1.08
🟢 Consistent with natural pulsar wind
The intercepted luminosity at these parameters is comparable to the companion's natural stellar luminosity (if any). The system is consistent with a natural black widow / redback pulsar.

What this tool does

This tool implements the energy budget formalism from Vidal (2016) — "Stellivore Extraterrestrials? Binary Stars as Living Systems" — applied to any pulsar–binary system. It computes the spin-down luminosity L_sd of the pulsar from its timing parameters, calculates the geometric fraction of that power intercepted by the companion, and places the result on the Kardashev scale.

Spider pulsars (black widows and redbacks) are binaries in which the pulsar wind is actively ablating a low-mass companion. Vidal proposes that such systems could, in principle, represent a stable energy-harvesting arrangement by an advanced civilisation: the pulsar acts as an energy source, and the companion is the "fuel." This tool tests whether the energetics of observed spider pulsars fall in a plausible range for such a scenario.

Key formulas

Spin-down luminosity: L_sd = 4π² I Ṗ / P³, with canonical moment of inertia I = 10⁴⁵ g cm² = 10³⁸ kg m².

Geometric interception fraction: f = R_c² / (4a²), where R_c is the companion radius and a is the orbital semi-major axis. This is the solid angle subtended by the companion divided by 4π.

Intercepted luminosity: L_int = f × L_sd. This is the maximum power the companion can intercept; actual coupling efficiency depends on the pulsar wind structure and magnetic field geometry.

Surface magnetic field: B_s = 3.2 × 10¹⁹ √(P Ṗ) gauss (assuming a dipole spin-down with I = 10⁴⁵ g cm²).

Characteristic age: τ_c = P / (2Ṗ) — an upper limit on the pulsar age assuming it was born spinning much faster.

Companion ablation timescale: M_c c² / L_int — the time to convert the companion's full rest-mass energy at the current irradiation rate. A very rough lower bound; real evaporation involves complex wind-stripping physics.

Epistemic status

The spin-down luminosity formula and binary geometry are 🔬 established physics. The interpretation of spider pulsars as starivores is Vidal's hypothesis: ⚠ Theoretical. It has been published in a peer-reviewed journal but is not mainstream astrophysics. Placing the system on the Kardashev scale is ✦ Engineering fiction.

Presets

PSR B1957+20 (the original "Black Widow"): P = 1.607 ms, Ṗ = 1.68×10⁻²⁰ s/s, orbital period 9.165 hr, companion mass ~ 0.025 M☉. Discovered by Fruchter et al. 1988.

PSR J2051−0827: P = 4.509 ms, Ṗ = 1.27×10⁻²⁰ s/s, orbital period 2.378 hr, companion mass ~ 0.027 M☉. Stappers et al. 1996.

PSR J1023+0038: P = 1.688 ms, Ṗ ≈ 5.59×10⁻²¹ s/s, orbital period 4.75 hr, companion mass ~ 0.2 M☉ (redback — Roche-lobe filling companion). Archibald et al. 2009.

References

Vidal, C. (2016). "Stellivore Extraterrestrials? Binary Stars as Living Systems." Acta Astronautica 128:251–256. DOI: 10.1016/j.actaastro.2016.06.038 Vidal, C. (2014). The Beginning and the End: The Meaning of Life in a Cosmological Perspective. Springer. DOI: 10.1007/978-3-319-05062-1 Fruchter, A. S., Stinebring, D. R., & Taylor, J. H. (1988). "A millisecond pulsar in an eclipsing binary." Nature 333:237–239. DOI: 10.1038/333237a0 Stappers, B. W. et al. (1996). "Probing the Eclipse of PSR J2051−0827." ApJ 465:L119. DOI: 10.1086/310145 Archibald, A. M. et al. (2009). "A Radio Pulsar/X-ray Binary Link." Science 324:1411. DOI: 10.1126/science.1172740

v1.0 — 2026-06-02 · Tool content may be revised as scientific knowledge evolves.