原始星际彗星的碎裂动力学：一项探索性多物理场模拟研究
Fragmentation Dynamics of Pristine Interstellar Comets: An Exploratory Multi-Physics Simulation Study
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中文总结 AI 辅助
通过多物理场模拟，发现原始星际彗星首次进入内太阳系时必然碎裂，碎片数量为涌现结果，质量损失主要受冰成分控制。
中文摘要 AI 辅助
我们提出了一个探索性数值模型，用于模拟原始星际彗星在首次穿过内太阳系期间的热演化和碎裂过程，并将其应用于一系列近日距（q=0.25--1.5 AU）和抗拉强度（σ_t=50--500 Pa）的网格。该模型跟踪单个彗核（M_0=2×10^12 kg，R_0≈1060 m，尘埃/冰=1，冰组成为35% CO、30% CO_2、15% CH_4、20% H_2O）沿连续双曲轨迹运动，求解初始30 K内部的热传导、能量平衡的多物种升华（含挥发性前沿退缩）、尘埃抬升和滞后地幔增长，以及地下气压失效准则，因此碎片数量是涌现结果而非数值输入。在我们的主要案例（q=1 AU，σ_t=100 Pa）中，彗核在模拟开始的3 AU处（第一天内r_h≈2.99 AU）即开始分裂，一旦亚毫米滞后沉积物部分封闭了升温的CO前沿——这意味着对于原始成分，起始点超出了我们的起始距离——并通过63次二元分裂解聚为至少64个碎片（我们的追踪上限），在近日点附近达到该上限，此前在53个天体处出现自限的近日点前平台，总质量损失为1.3%；升华受能量限制，因此储库消耗保持适度（CO 2%、CH_4 2%、CO_2 1%、H_2O <0.1%），破碎体几乎保留其全部质量作为碎片群；质量预算闭合至机器精度。在探索的网格中，没有任何组合使彗核保持完整，质量损失对q和σ_t的依赖较弱（0.8--1.7%），而对成分依赖强烈：耗尽的、类似67P的冰在q=1 AU时将质量损失降至0.1%。
英文摘要
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 ($σ_t=50$--$500$~Pa). A single nucleus ($M_0=2\times10^{12}$~kg, $R_0\approx1.06$~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, $σ_t=100$~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 $σ_t$ 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 $σ_t$, 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.
发表机构
- College of Charleston（查尔斯顿学院）
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