AI Insight
This computational study models how pristine interstellar comets fragment during their first passage through the inner Solar System. The simulations show that a 1-kilometer comet begins fragmenting beyond 3 AU due to gas pressure buildup beneath a dust mantle, ultimately splitting into dozens of pieces while losing only 1-3% of its total mass through sublimation. The model found that all simulated interstellar comets disaggregated regardless of strength or composition, unlike Jupiter-family comets with similar properties that survive multiple perihelion passages, suggesting the current sealing mechanisms in the model may overestimate fragmentation.
Why it matters
Understanding interstellar comet fragmentation helps explain observed behaviors like 'Oumuamua's non-gravitational acceleration and comet Borisov's survival, while improving predictions for detecting and characterizing future interstellar visitors. The findings also have implications for planetary defense by clarifying how pristine icy bodies respond to solar heating.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Abstract: We present an exploratory numerical model for the thermal evolution and fragmentation of pristine interstellar comets on a first passage through the inner Solar System, applied over a grid of perihelion distances ($q=0.25$–$1.5$~AU) and tensile strengths ($sigma_t=50$–$500$~Pa). A single nucleus ($M_0=2times10^{12}$~kg, $R_0approx1.06$~km, dust/ice $=1$, ices 35% CO, 30% CO$_2$, 15% CH$_4$, 20% H$_2$O) follows a hyperbolic trajectory from an initially 30~K state, with heat conduction, energy-balanced multi-species sublimation, dust lifting and lag-mantle growth, and a subsurface gas-pressure failure criterion, so that fragmentation is emergent rather than prescribed. In the primary case ($q=1$~AU, $sigma_t=100$~Pa) splitting begins at the 3~AU starting distance, once a sub-millimeter lag deposit partially confines the warming CO front; 63 binary splittings follow, with a self-limited plateau at 53 bodies before perihelion and the 64-body tracking cap reached near perihelion. Sublimation is energy-limited: total mass loss is 1.3%, volatile depletions are at most a few per cent, and most of the mass survives as a fragment swarm; the mass budget closes to machine precision. Across the grid, mass loss (0.8–1.7%) depends weakly on $q$ and $sigma_t$ but strongly on composition, falling to 0.1% for depleted, 67P-like ices. Yet every case, including the depleted class, disaggregates, whereas Jupiter-family comets of similar composition survive repeated perihelia, so the sealing prescription over-fragments. We regard the composition ranking, the insensitivity to $sigma_t$, percent-level mass loss, and an onset beyond 3~AU as robust, and defer absolute survival predictions to calibration against well-observed comets. Mantle insulation suppresses outbound activity, producing an inbound–outbound asymmetry.