A5 5 Between Suns: The Empty Space Between Oort Clouds

Abstract

We estimate whether the Sun’s outer Oort cloud overlaps the nearest stellar system’s (Alpha
Centauri’s) analogous reservoir, i.e., its hypothetical outer Oort cloud. Because Oort clouds are
theoretical and not directly imaged [1], we adopt canonical sizes and a mass-scaling motivated
by tidal/Hill arguments [2]. Using present-day separations D ∼ (2.6− 2.76) × 10⁵ AU [3] and
R_OC ∼ 10⁵ AU [4] for the Sun (with the neighbour’s radius R_OC,⋆ = R_OC,⊙(M_⋆/M_⊙)^1/3 [2]), we
find no overlap. Along the line connecting the systems, the linear gap is ∼ 3.4× 10⁴
− 5.0× 10⁴ AU. This remains true when enforcing the gravitational balance (L1) limit and even under an extreme, enlarged Solar Oort cloud. This provides a clear gravitational boundary for the outer Solar System and a baseline for interpreting long-period comets and interstellar visitors.