{"ID":23646982,"CreatedAt":"2026-09-18T07:39:37.512926072Z","UpdatedAt":"2026-09-18T07:39:37.512926072Z","DeletedAt":null,"paper_url":"https://arxiv.org/abs/2609.20773","arxiv_id":"2609.20773","title":"Fragmentation Dynamics of Pristine Interstellar Comets: An Exploratory Multi-Physics Simulation Study","abstract":"We present an exploratory numerical model for the thermal evolution and fragmentation of pristine interstellar comets during a first passage through the inner Solar System, and we apply it across a grid of perihelion distances (q=0.25--1.5~AU) and tensile strengths (σ_t=50--500~Pa). The model follows a single nucleus (M_0=2\\times10^{12}~kg, R_0\\approx1060~m, dust/ice =1, ice composition 35\\% CO, 30\\% CO_2, 15\\% CH_4, 20\\% H_2O) along a continuous hyperbolic trajectory, solving heat conduction into an initially 30~K interior, energy-balanced multi-species sublimation with retreating volatile fronts, dust lifting and lag-mantle growth, and a subsurface gas-pressure failure criterion, so that the number of fragments is an emergent outcome rather than a numerical input. In our primary case (q=1~AU, σ_t=100~Pa) the nucleus begins splitting essentially at the 3~AU start of the simulation ($r_h=$~2.99~AU within the first day), as soon as a sub-millimeter lag deposit partially confines the warming CO front---implying that for pristine composition the onset lies beyond our starting distance---and disaggregates through 63 binary splittings into at least 64 fragments---our tracking cap, reached near perihelion after a self-limited pre-perihelion plateau at 53 bodies---with 1.3\\% total mass loss; sublimation is energy-limited, so reservoir depletions stay modest (CO 2\\%, CH_4 2\\%, CO_2 1\\%, H_2O \u003c0.1\\%) and the shattered body retains almost all of its mass as a fragment swarm; the mass budget closes to machine precision. Across the explored grid, no combination leaves the nucleus intact, and mass loss depends only weakly on q and σ_t (0.8--1.7\\%) while depending strongly on composition: depleted, 67P-like ices reduce mass loss to 0.1\\% at q=1~AU.","short_abstract":"We present an exploratory numerical model for the thermal evolution and fragmentation of pristine interstellar comets during a first passage through the inner Solar System, and we apply it across a grid of perihelion distances (q=0.25--1.5~AU) and tensile strengths (σ_t=50--500~Pa). The model follows a single nucleus (...","url_abs":"https://arxiv.org/abs/2609.20773","url_pdf":"https://arxiv.org/pdf/2609.20773v1","authors":"[\"Behrooz Karamiqucham\"]","published":"2026-09-17T17:47:12Z","proceeding":"astro-ph.EP","tasks":"[\"astro-ph.EP\"]","methods":"[\"LoRA\"]","has_code":false}